the consort statement: application within and adaptations ...€¦ · the consort statement:...

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The CONSORT Statement: Application within and adaptations for orthodontic trials Nikolaos Pandis, a Padhraig S. Fleming, b Sally Hopewell, c and Douglas G. Altman d Bern, Switzerland, Corfu, Greece, London and Oxford, United Kingdom, and Paris, France High-quality randomized controlled trials (RCTs) are an integral part of evidence-based medicine. RCTs are the bricks and mortar of high-quality systematic reviews, which are important determinants of health care policy and clinical practice. For published research to be used most effectively, investigators and authors should follow the guidelines for accurate and transparent reporting of RCTs. The consolidated standards of reporting trials (CONSORT) statement and its extensions are among the most widely used reporting guidelines in biomedical research. CONSORT was adopted by the American Journal of Orthodontics and Dentofacial Orthopedics in 2004. Since 2011, this Journal has been actively implementing compliance with the CONSORT reporting guidelines. The objective of this explanatory article is to highlight the rele- vance and implications of the various CONSORT items to help authors to achieve CONSORT compliance in their research submissions of RCTs to this and other orthodontic journals. (Am J Orthod Dentofacial Orthop 2015;147:663-79) R andomized controlled trials (RCTs) are an integral part of evidence-based medicine. Readers of re- ports of RCTs must be able to understand exactly how the trial was conducted to assess its relevance and methodologic rigor. Two key principles are that the trials could be replicated from the information provided and that the methods and ndings should be described in enough detail to allow inclusion of the trial in a subse- quent systematic review. 1 The consolidated standards of reporting trials (CONSORT) statement was developed to help improve the reporting of RCTs with guidance to researchers pre- paring reports of their clinical trials. The CONSORT checklist consists of 25 items covering all key aspects of clinical trials, setting standards on how to report the design, conduct, analysis, and interpretation of such studies. 2 Several extensions to the main CONSORT guidelines cover more complicated designs such as clus- ter randomized and noninferiority trials; updated infor- mation is available at the CONSORT Web site (http:// www.consort-statement.org/extensions). Over 600 biomedical journals, including the American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO) in 2004, have adopted the CONSORT guidelines, and many have also adopted additional CONSORT guidelines on abstract reporting. 3 Despite the widespread accep- tance of these recommendations, there remains consid- erable scope for improving the reporting of clinical trials. 4-8 The AJO-DO recognized that adoption does not guarantee compliance with the CONSORT guidelines and in 2011 implemented a scheme geared at improving compliance with CONSORT and so improve the reporting of RCTs in the Journal. This scheme includes videos, links to the CONSORT Web site, and active guidance for authors submitting reports of RCTs regarding compliance with the CONSORT guidelines. More recently, the reporting of RCTs by the AJO-DO has been reformatted with the introduction of subheadings to promote complete reporting and, by extension, to allow more efcient data extraction during the system- atic review process. Since these changes were introduced in the AJO-DO, published RCTs have shown dramatic improvements in a Assistant professor, Department of Orthodontics and Dentofacial Orthopedics, Dental School, Medical Faculty, University of Bern, Bern, Switzerland; private practice, Corfu, Greece. b Senior clinical lecturer and honorary consultant, Barts and the London School of Medicine and Dentistry, Queen Mary University, London, United Kingdom. c Senior research fellow, Centre for Statistics in Medicine, Nufeld Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom; senior scientist, Centre d'Epid emiologie Clinique, Uni- versit e Paris Descartes, INSERM U1153, France. d Professor, Centre for Statistics in Medicine, Nufeld Department of Orthopae- dics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom. All authors have completed and submitted the ICMJE Form for Disclosure of Po- tential Conicts of Interest, and none were reported. Address correspondence to: Nikolaos Pandis, 29 P. Zaropoulou Str, Corfu 49100, Greece; e-mail, [email protected]. Submitted, revised and accepted, March 2015. 0889-5406/$36.00 Copyright Ó 2015 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2015.03.014 663 CENTENNIAL SPECIAL ARTICLE

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Page 1: The CONSORT Statement: Application within and adaptations ...€¦ · The CONSORT Statement: Application within and adaptations for orthodontic trials Nikolaos Pandis,a Padhraig S

The CONSORT Statement: Application withinand adaptations for orthodontic trials

Nikolaos Pandis,a Padhraig S. Fleming,b Sally Hopewell,c and Douglas G. Altmand

Bern, Switzerland, Corfu, Greece, London and Oxford, United Kingdom, and Paris, France

High-quality randomized controlled trials (RCTs) are an integral part of evidence-based medicine. RCTs arethe bricks and mortar of high-quality systematic reviews, which are important determinants of health carepolicy and clinical practice. For published research to be used most effectively, investigators and authorsshould follow the guidelines for accurate and transparent reporting of RCTs. The consolidated standardsof reporting trials (CONSORT) statement and its extensions are among the most widely used reportingguidelines in biomedical research. CONSORT was adopted by the American Journal of Orthodontics andDentofacial Orthopedics in 2004. Since 2011, this Journal has been actively implementing compliancewith the CONSORT reporting guidelines. The objective of this explanatory article is to highlight the rele-vance and implications of the various CONSORT items to help authors to achieve CONSORT compliancein their research submissions of RCTs to this and other orthodontic journals. (Am J Orthod DentofacialOrthop 2015;147:663-79)

Randomized controlled trials (RCTs) are an integralpart of evidence-based medicine. Readers of re-ports of RCTs must be able to understand exactly

how the trial was conducted to assess its relevance andmethodologic rigor. Two key principles are that the trialscould be replicated from the information provided andthat the methods and findings should be described inenough detail to allow inclusion of the trial in a subse-quent systematic review.1

The consolidated standards of reporting trials(CONSORT) statement was developed to help improvethe reporting of RCTs with guidance to researchers pre-paring reports of their clinical trials. The CONSORTchecklist consists of 25 items covering all key aspects

of clinical trials, setting standards on how to report thedesign, conduct, analysis, and interpretation of suchstudies.2 Several extensions to the main CONSORTguidelines cover more complicated designs such as clus-ter randomized and noninferiority trials; updated infor-mation is available at the CONSORT Web site (http://www.consort-statement.org/extensions). Over 600biomedical journals, including the American Journal ofOrthodontics and Dentofacial Orthopedics (AJO-DO)in 2004, have adopted the CONSORT guidelines, andmany have also adopted additional CONSORT guidelineson abstract reporting.3 Despite the widespread accep-tance of these recommendations, there remains consid-erable scope for improving the reporting of clinicaltrials.4-8

The AJO-DO recognized that adoption does notguarantee compliance with the CONSORT guidelinesand in 2011 implemented a scheme geared at improvingcompliance with CONSORT and so improve the reportingof RCTs in the Journal. This scheme includes videos,links to the CONSORT Web site, and active guidancefor authors submitting reports of RCTs regardingcompliance with the CONSORT guidelines. Morerecently, the reporting of RCTs by the AJO-DO hasbeen reformatted with the introduction of subheadingsto promote complete reporting and, by extension, toallow more efficient data extraction during the system-atic review process.

Since these changes were introduced in the AJO-DO,published RCTs have shown dramatic improvements in

aAssistant professor, Department of Orthodontics and Dentofacial Orthopedics,Dental School, Medical Faculty, University of Bern, Bern, Switzerland; privatepractice, Corfu, Greece.bSenior clinical lecturer and honorary consultant, Barts and the London School ofMedicine and Dentistry, Queen Mary University, London, United Kingdom.cSenior research fellow, Centre for Statistics in Medicine, Nuffield Department ofOrthopaedics, Rheumatology and Musculoskeletal Sciences, University ofOxford, United Kingdom; senior scientist, Centre d'Epid�emiologie Clinique, Uni-versit�e Paris Descartes, INSERM U1153, France.dProfessor, Centre for Statistics in Medicine, Nuffield Department of Orthopae-dics, Rheumatology and Musculoskeletal Sciences, University of Oxford, UnitedKingdom.All authors have completed and submitted the ICMJE Form for Disclosure of Po-tential Conflicts of Interest, and none were reported.Address correspondence to: Nikolaos Pandis, 29 P. Zafiropoulou Str, Corfu49100, Greece; e-mail, [email protected], revised and accepted, March 2015.0889-5406/$36.00Copyright � 2015 by the American Association of Orthodontists.http://dx.doi.org/10.1016/j.ajodo.2015.03.014

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reporting quality; this improvement reflects successfulinteractions among the editors, reviewers, and authors.9

All published trials submitted between 2011 and 2013reported 33 of the 37 CONSORT items and subitems.CONSORT items referring to changes to methods (3b),changes to outcomes after the trial commenced (6b),interim analysis (7b), and trial stopping (14b) were notfully reported. However, there is still a need to improvethe reporting in the initial submissions to limit theneed for editorial input to improve CONSORT compli-ance. The objectives of this article are to explain the re-quirements of the AJO-DO for RCT submissions and todescribe and communicate the importance of eachitem in the CONSORT checklist as it relates to orthodon-tics. This article is based on the CONSORT 2010 explana-tion and elaboration document for reporting parallelgroup randomized trials.2 A CONSORT-compliant pub-lished RCT has been uploaded on the AJO-DO Website (Annotated RCT Sample Article) and will serve asthe illustrative example.

DESCRIPTION OF THE CHECKLIST ITEMS ANDIMPORTANCE

The following explanations are based on the expla-nation and elaboration CONSORT document and areappropriately adapted to better target the AJO-DO'saudience (Table I).2

TITLE AND ABSTRACT

CONSORT item 1a is “identification as a random-ized trial in the title.”

Example: “Survival of bonded lingual retainers(outcome) in orthodontic patients (participants) withchemical (intervention) or photo polymerization (com-parison) over a 2-year period: A single-center, random-ized controlled clinical trial.”

Explanation: To help ensure that a study is appropri-ately indexed and easily identified, authors should usethe word “randomized” in the title to indicate that theparticipants were randomly assigned to their comparisongroups.10 Authors are also encouraged (not a CONSORTitem) to structure the title in the PICO1 format,providing information about participants, interventions,comparisons, and outcomes. The 1 sign indicates thepossible inclusion of additional information pertainingto blinding, number of centers, time, and so on.

CONSORT item 1b is “structured summary of trialdesign, methods, results, and conclusions” (forspecific guidance, see CONSORT for abstracts).

Explanation: There is specific guidance for reportingabstracts of RCTs (Table II). Well-written and detailedabstracts clearly describing the trial facilitate the initial

assessment of an article and aid the retrieval of trialsfrom databases for inclusion in systematic reviews. Theabstract is the only component of an article that isread by many clinicians; hence, the accuracy and thequality of its information are critical. Reporting of theabstract items will be considered at the end of thisarticle, since almost all information relevant to theabstract will be discussed in detail in under the mainCONSORT guideline items.

INTRODUCTION

The introduction includes the background and theobjectives.

Background and objectives

CONSORT item 2a is “scientific background andexplanation of rationale.”

Example: “A significant problem continues torelate to bond failures, estimated at 6% to 25%, de-pending on the placement technique and the observa-tion period. Although light-cured materials offerlonger working times and improved moisture control,no randomized controlled trial has been publishedinvestigating the importance of these theoretical ad-vantages.”

Explanation: It is good practice at the planning stageof the trial to first search the literature to identify theavailable evidence on the topic of interest. This evidencecan be limited or abundant, and identification of a high-quality systematic review, if available, is desirable. Arecent high-quality systematic review, which summa-rizes the existing evidence, can serve as a reference interms of what is known and what remains unclearregarding the efficacy and safety of the intervention ofinterest. The Declaration of Helsinki considers researchon human subjects without thorough knowledge ofthe existing literature as unethical. It is also unethicalto plan a trial to answer a question that has alreadybeen answered. A trial is justified when there is genuineuncertainty (equipoise), based on the existing evidence,regarding the effectiveness of the intervention athand.11

In the RCT example, a systematic review is not cited,but the authors explicitly stated that no RCT has beenpublished investigating the theoretical advantages oflight curing vs chemical curing.

CONSORT item 2b is “specific objectives orhypotheses.”

Example: “In this study, we aimed to compare thesurvival of mandibular lingual retainers placed by usingeither chemical or photopolymerization after orthodon-tic treatment.”

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Table I. CONSORT 2010 checklist of information to include when reporting a randomized trial2

Section/topic Item (n) Checklist itemTitle and abstract

1a Identification as a randomized trial in the title1b Structured summary of trial design, methods, results, and conclusions (for specific guidance, see

CONSORT for abstracts)IntroductionBackground and objectives 2a Scientific background and explanation of rationale

2b Specific objectives or hypothesesMethodsTrial design 3a Description of trial design (such as parallel, factorial) including allocation ratio

3b Important changes to methods after trial commencement (such as eligibility criteria), withreasons

Participants 4a Eligibility criteria for participants4b Settings and locations where the data were collected

Interventions 5 Interventions for each group with sufficient details to allow replication, including how and whenthey were actually administered

Outcomes 6a Completely defined prespecified primary and secondary outcome measures, including how andwhen they were assessed

6b Any changes to trial outcomes after the trial commenced, with reasonsSample size 7a How sample size was determined

7b When applicable, explanation of any interim analyses and stopping guidelinesRandomizationSequence generation 8a Method used to generate the random allocation sequence

8b Type of randomization; details of any restriction (such as blocking and block size)Allocation concealment 9 Mechanism used to implement the random allocation sequence (eg, sequentially numbered

containers), describing any steps taken to conceal the sequence until interventions wereassigned

Implementation 10 Who generated the random allocation sequence, who enrolled participants, and who assignedparticipants to interventions

Blinding 11a If done, who was blinded after assignment to interventions (eg, participants, care providers,those assessing outcomes) and how

11b If relevant, description of the similarity of interventionsStatistical methods 12a Statistical methods used to compare groups for primary and secondary outcomes

12b Methods for additional analyses, such as subgroup analyses and adjusted analysesResultsParticipant flow (diagram isstrongly recommended)

13a For each group, numbers of participants who were randomly assigned, received intendedtreatment, and were analyzed for the primary outcome

13b For each group, losses and exclusions after randomization, with reasonsRecruitment 14a Dates defining the periods of recruitment and follow-up

14b Why the trial ended or was stoppedBaseline data 15 A table showing baseline demographic and clinical characteristics for each groupNumbers analyzed 16 For each group, number of participants (denominator) included in each analysis, and whether

the analysis was by original assigned groupsOutcomes and estimation 17a For each primary and secondary outcome, results for each group, and the estimated effect size

and its precision (such as 95% CI)17b For binary outcomes, presentation of both absolute and relative effect sizes is recommended

Ancillary analyses 18 Results of any other analyses performed, including subgroup analyses and adjusted analyses,distinguishing prespecified from exploratory

Harms 19 All important harms or unintended effects in each group (for specific guidance, see CONSORTfor harms)

DiscussionLimitations 20 Trial limitations, addressing sources of potential bias, imprecision, and, if relevant, multiplicity

of analysesGeneralizability 21 Generalizability (external validity, applicability) of the trial findingsInterpretation 22 Interpretation consistent with results, balancing benefits and harms, and considering other

relevant evidenceOther informationRegistration 23 Registration number and name of trial registryProtocol 24 Where the full trial protocol can be accessed, if availableFunding 25 Sources of funding and other support (eg, supply of drugs) and the role of funders

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Explanation: The objectives are the questions thatthe trial was designed to answer. They often relateto the efficacy of a particular therapeutic or preven-tive intervention. Hypotheses are prespecified ques-tions being tested to help meet the objectives.Hypotheses are more specific than objectives andare amenable to explicit statistical evaluations. Inpractice, objectives and hypotheses are not alwayseasily differentiated.

METHODS

Trial design

CONSORT item 3a is “description of the trialdesign (eg, parallel, factorial) including the allocationratio.”

Example: “This was a parallel-group, randomized,active controlled trial with a 1:1 allocation ratio.”

Explanation: The most common type of trialdesign is the parallel design; however, other designssuch as cross-over, cluster randomized, noninferiority,factorial, and hybrids of those exist and should bespecified. A study design commonly used in dentistryis the split-mouth design,12 as well as studiesincluding elements of clustered designs. Such designsoccur when several observations are collected fromeach patient from multiple sites and tissues such asthe number of teeth or periodontal sites or struc-tures.13 Different trial designs have characteristicsthat may influence the conduct and analysis of the

trial; these details should, therefore, be describedclearly. It is important that specific details (designand allocation ratio) are given as shown under thissubheading.

CONSORT item 3b is “important changes tomethods after trial commencement (such as eligibilitycriteria), with reasons.”

Example: “No changes to the methods after trialcommencement occurred.”

Explanation: Changes between the study protocoland how the trial was actually done are common andshould be documented appropriately. Possible reasonsfor changes—eg, to eligibility criteria or duration offollow up—include new external evidence, inability torecruit a sufficient number of patients, and financialconstraints. For some “adaptive” trials, the protocolallows for limited changes following prespecified rules,when the sample size and duration of the trial are notdetermined before commencement. The protocol shouldindicate the adjustments planned under the differentchange scenarios, and the changes should be docu-mented, explained, and justified in the publishedarticle.14 Any modifications to the trial design shouldbe fully reported to help the reader interpret the results,whether they were anticipated in the protocol or inresponse to changing circumstances.

The RCT at hand reported no changes after thecommencement of the trial; however, no published pro-tocol allowed this to be verified, and this is reported atthe end of the abstract.

Table II. CONSORT for abstracts checklist of items to include when reporting a randomized trial3

Item DescriptionTitle Identification of the study as randomizedAuthors* Contact details for the corresponding authorTrial design Description of the trial design (eg, parallel, cluster, noninferiority)MethodsParticipants Eligibility criteria for participants and the settings where the data were collectedInterventions Interventions intended for each groupObjective Specific objective or hypothesisOutcome Clearly defined primary outcome for this reportRandomization How participants were allocated to interventionsBlinding (masking) Whether participants, care givers, and those assessing the outcomes were blinded to group assignments

ResultsNumbers randomized Number of participants randomized to each groupRecruitment Trial statusNumbers analyzed Number of participants analyzed in each groupOutcome For the primary outcome, a result for each group and the estimated effect size and its precisionHarms Important adverse events or side effects

Conclusions General interpretation of the resultsTrial registration Registration number and name of trial registerFunding Source of funding

*This item is specific to conference abstracts.

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Participants

CONSORT item 4a is “eligibility criteria for partic-ipants.”

Example: “The following selection criteria wereapplied: no active caries, restorations, or fractures onthe mandibular anterior teeth; no periodontal disease;and adequate oral hygiene.”

Explanation: Eligibility criteria and information onparticipants and settings should be outlined clearlybecause they have implications for the relevance of thetrial results to other settings (generalizability). Becauseeligibility criteria are applied before randomization,they do not affect the internal validity (methodologicquality) of a trial.15 The common distinction between in-clusion and exclusion criteria is unnecessary; the samecriterion can be phrased to include or exclude partici-pants.16

CONSORT item 4b is “settings and locations wherethe data were collected.”

Example: “Consecutive patients who had completedorthodontic treatment with fixed appliances were re-cruited at the private practice of the first author (N.P.)from April 2009 to November 2010.”

Explanation: A clear description of the setting and lo-cations where the data were collected is important toallow the reader to decide whether the findings are rele-vant to her or his own setting. Information on thegeographic location, the number of participating cen-ters, the available facilities, the involved care providers,and their levels of expertise should also be clearlydescribed. Trial results may differ substantially, forexample, between centers with state-of-the-art facilitieswith highly trained personnel and studies undertaken byrelative novices in poorly equipped clinics.15

Interventions

CONSORT item 5 is “interventions for each groupwith sufficient details to allow replication, includinghow and when they were actually administered.”

Example: “All patients received a soft bonded lingualretainer of 0.022-in (Tru-Chrome multi-stranded wire;Rocky Mountain Orthodontics, Denver, Colo) that wasfabricated intraorally. In the chemical polymerizationgroup, Maximum Cure 2-part liquid adhesive (RelianceOrthodontic Products, Itasca, Ill) was mixed and appliedon the wire and the teeth, and Excel 2-part paste (Reli-ance Orthodontic Products) was mixed, loaded on a sy-ringe dispenser, and applied. The dental floss wasremoved after 7 minutes. In the photopolymerizationgroup, a light-cured liquid (Assure; Reliance OrthodonticProducts) and a paste in 2 layers (Flow-Tain; RelianceOrthodontic Products) were placed on the wire and the

adjacent enamel, and light-cured for 9 seconds per toothwith a plasma light (Ortholite; 3M Unitek, Monrovia,Calif).”

Explanation: A clear description of each interventionin sufficient detail to allow a knowledgeable researcherto duplicate the experiment should be provided.17 Forexample, in a multicenter trial, as a minimum, the exactmethod of standardization of the administration, theduration, and the timing of the treatment should be out-lined.18 A pharmacologic intervention would requireexplanation of the drug administered in conjunctionwith the mode of delivery, dosage, and frequency, andwhether the control or placebo was indistinguishablefrom the “active pill” in terms of shape, color, smell,and taste. For other types of interventions, the CONSORTextension for nonpharmacologic trials describes thereporting requirements.19 Some important issues arethe standardization of the delivery of the interventions,description of the various components of the interven-tions, and how adherence of the care providers to theprotocol was assessed. A clear description further facili-tates the implementation of valid comparisons andinformed decisions regarding the inclusion of the pri-mary study in systematic reviews.17

Outcomes

CONSORT item 6a is “completely defined prespeci-fied primary and secondary outcome measures,including how and when they were assessed.”

Example: “The main outcome was any first-time fail-ure of the lingual retainer. The secondary outcome wasthe pattern of failure based on the adhesive remnant.The patients were advised to visit the orthodontistinitially at 1, 3, and 6 months after retainer placement,followed by scheduled appointments at 12, 18, and 24months. When scheduled appointments were unfeasi-ble, particularly approaching the end of the trial,an assessment of retainer integrity was made over thetelephone.”

Explanation: It is common for trials to have severaloutcomes, often identified as primary and secondary.All outcomes should be clearly defined and prespecifiedwith an explicit description of how and when they wereassessed. The definition of each outcome should be clearenough to allow other investigators to use the sameoutcome in a trial or to be confident of the similaritiesand differences of the outcome in the context of a sys-tematic review. Declaration of prespecified outcomes,especially the primary outcome, is important, since,like registration and protocol prepublication, it mitigatesagainst the problem of selective reporting of “inter-esting” outcomes. This is more likely when multiple

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outcomes or multiple time points of data collectionare planned.20 Additionally, recording of several out-comes, and consequently multiple testing, invokesthe problems associated withmultiplicity andmisleadinginterpretations.21

When assessing the evidence for or against the effec-tiveness of an intervention, the balance of benefits andharms is an important consideration. A clear descriptionof harms that were recorded should be provided.22 Innonpharmacologic trials, it is particularly important tospecify the skills and the number of persons assessingthe outcomes.

CONSORT item 6b is “any changes to trial out-comes after the trial commenced, with reasons.”

Example: “There were no outcome changes after trialcommencement.”

Explanation: Reviews of publications show thatdiscrepancies between planned and presented outcomesare common.23 Outcomes initially planned to be theprimary outcomes in the original trial protocol may beportrayed as secondary outcomes, whereas new primaryoutcomes can be introduced in the published article.Selective outcome reporting and presentation of “inter-esting” findings has also been documented.20 Therefore,clear descriptions of any outcome changes with thereasons for the alterations will enhance transparency.No outcome changes are reported in the RCT described;however, there is no prepublished protocol to confirmthis.

Sample size

CONSORT item 7a is “how sample size was deter-mined.”

Example: “Calculation of sample size was based onthe ability to detect a clinically relevant difference inthe risk of first-time failure (primary outcome) of 20%between the 2 trial arms (15% vs 35% with a 5 0.05and power of 85%). Foek et al found a 35% failurerate for light-cured lingual retainers; we used this valueas our reference for the sample calculation. This calcula-tion indicated that 93 participants were required in eacharm; this was rounded up to 110 to account for losses tofollow-up.”

Explanation: RCTs should have enough power todetect a clinically important difference between thetreatment groups if such a difference exists, or toconfirm the lack of a difference. It is an obligation ofthe investigators to conduct appropriate sample-sizecalculations driven by clinical importance and reason-able assumptions.

Authors should provide enough information so that aknowledgeable reader can reproduce the sample-size

calculation.24,25 The sample-size calculation is usuallybased on the primary outcome, which should be clearlyidentified. For continuous outcomes, the authors shouldreport the expected result in the control group, theexpected difference of the intervention group from thecontrol, the standard deviations, and the alpha andpower levels. For binary outcomes, the same informationis required, except for the standard deviation. In designswhere clustering effects are expected, the value of theintracluster correlation coefficient should be provided.26

For split-mouth designs, common in orthodontics, theassumed correlations between sites should be speci-fied.12,27 Finally, any provisions for expected losses tofollow-up should also be described. Authors shouldideally explain the rationale for the values used in thecalculation.

A post hoc analysis to justify the sample size isconsidered inappropriate: power can be judged byinspecting the effect size and confidence intervals andthe uncertainty that they convey.28

CONSORT item 7b is “when applicable, explanationof any interim analyses and stopping guidelines.”

Example: “Not applicable.”Explanation: Participants can be recruited and

treated over a prolonged period. If an obvious differencebetween interventions emerges early in the trial, thestudy may be stopped prematurely for ethical reasons.This eventuality can be addressed by inspection ofthe interim results, ideally by an independent data-monitoring committee. However, performing multiplestatistical examinations without appropriate correctionscan lead to erroneous results and interpretations.21 Au-thors should report whether they or a data-monitoringcommittee took several “looks” at the data; if so, howmany were there, what triggered them, what statisticalmethods were used (including any formal stoppingrule), and whether they were planned before the startof the trial, before the data-monitoring committee sawany interim data by allocation, or some time thereafter.

No interim analyses or stopping guidelines werereported in the example study.

RANDOMIZATION

Randomization is the key advantage of RCTscompared with other prospective studies. Randomiza-tion in clinical trial methodology has a specific meaningand should be implemented so that neither the investi-gator nor the participants can predict the next treatmentallocation. The terms “alternating allocation,”“randomly assigned,” and allocation based on somedeterministic measure—eg, date of birth or day of theweek—are not considered robust or explicit enough,

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although they are often encountered in the dental liter-ature.5,29 Such inappropriate allocation schemes are nottrue randomization and have been associated withbiased results. The process of randomization requirestreatment allocation completely by chance, with amechanism to conceal the treatment allocation beforeit actually occurs.

Sequence generation

CONSORT item 8a is “method used to generate therandom allocation sequence.”

Example: “Randomization was accomplished byusing the “-ralloc-” command20 in Stata software(StataCorp, College Station, Tex).”

Explanation: Random number generation is usuallyproduced by using random tables or software capableof producing random sequences. It is important thatauthors clearly describe how the random number listwas generated for the reader to make a judgment as towhether the method was appropriate.

CONSORT item 8b is “type of randomization; de-tails of any restriction (such as blocking and blocksize).”

Example: “. in random permuted blocks of 20 pa-tients, ensuring equal distribution in the 2 groups.”

Explanation: Several methods such as simple andpermuted block randomization, stratified randomiza-tion, and minimization have been used in dentalresearch.29 Simple randomization resembles a toss of acoin and, although it is the most secure method becauseit is truly random, in small trials the probability of un-equal sizes of the treatment arms is high. Use ofpermuted blocks ensures nearly balanced treatmentgroups, depending on the block size, whereas stratifiedrandomization or minimization ensures balance oftreatment groups with respect to the important outcomepredictors.

Authors should clearly describe the randomizationmethod and any restrictions applied. When permutedblocks are used, this should be indicated along withthe block size and whether block size was fixed orvariable, since this influences the predictability ofsubsequent allocations.

Allocation concealment

CONSORT item 9 is “mechanism used to imple-ment the random allocation sequence (eg, sequen-tially numbered containers), describing any stepstaken to conceal the sequence until interventionswere assigned.”

Example: “Allocation concealment was achievedwith sequentially numbered, opaque, sealed envelopes

containing the treatment allocation cards, which wereprepared before the trial.”

Explanation: Allocation concealment ensures unpre-dictability of treatment allocation by patients and inves-tigators and is always feasible, unlike blinding, which isoften difficult to implement in dental trials.30 Methodsof allocation concealment may include the use ofsequentially numbered sealed opaque envelopes, or allo-cations assigned from an external center. The bestmethod to conceal the allocation is to use an indepen-dent and centralized assignment protocol. With thelatter, the randomization lists are generated and heldsecurely in remote locations, thus reducing the chanceof subverting the process.

Implementation

CONSORT item 10 is “who generated the randomallocation sequence, who enrolled participants, andwho assigned participants to interventions?”

Example: “Baseline information was written on theoutside before opening the envelope. The practicemanager was responsible for opening the next envelopein sequence and implementing the randomizationprocess.”

Explanation: Implementation of randomization per-tains to who, when, where, and how the procedures ofrandomization (generation of randomization lists, allo-cation concealment, and treatment assignment) wereimplemented. In small studies, it is likely that the sameinvestigators perform all tasks. However, it would bepreferable to have different people perform the separaterandomization procedures, because this would decreasethe chance of biasing the process.

Lack of appropriate randomization and allocationconcealment may introduce bias, thus rendering theresults of the study questionable.30 Among the variousstudy designs, the RCT is considered to provide the high-est quality of evidence; however, there is substantialevidence in the biomedical literature including dentistrythat randomization and RCT quality, in general, aresuboptimal, and that often clinical trials described asRCTs are mislabeled.5,31 Therefore, a clear descriptionof all the elements of randomization is required toallow the knowledgeable reader to assess the rigor ofthe methods.

Blinding

CONSORT item 11a is “if done, who was blindedafter assignment to interventions (eg, participants,care providers, those assessing outcomes) and how.”

Example: “Blinding of either patient or operator wasnot possible.”

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Explanation: Authors should describe who wasblinded (patients, investigators, data assessors, or dataanalysts). Differential follow-up (performance bias),outcome recording (detection bias), losses to follow-up(attrition bias), and biased data analysis associatedwith lack of blinding may bias the trial results.32 Termi-nology regarding blinding varies and is confusing;therefore, a clear explanation is encouraged, ratherthan use of terms such as “single blind” or “doubleblind.”33 Giving specific information allows the readerto better assess the potential risk of bias. If there are mul-tiple outcomes, a clear description of blinding is requiredfor each outcome.

CONSORT item 11b is “if relevant, description ofthe similarity of interventions.”

Example: “Blinding of either patient or operator wasnot possible; however, outcome assessment was blindbecause it was not possible to distinguish the light curedfrom the chemically cured composite.”

Explanation: Authors should clearly report, if appli-cable, any similarities between interventions that facili-tate blinding. In dentistry, interventions often differwidely; however, blind outcome assessment can befeasible if, for example, it is done by a person not other-wise involved in the trial, and even when interventionsare grossly dissimilar. Testing for the effectiveness ofblinding is not recommended because responses mayreflect accurate assumptions about the efficacy of theintervention34; known compromises to blinding suchas unblinding any participants at any point during theconduct of a trial should be reported.

Statistical methods

CONSORT item 12a is “statistical methods used tocompare groups for primary and secondary out-comes.”

Example: “Comparisons of the survival of lingualretainers bonded with the 2 techniques were carriedout with statistical methods for survival analysis. Thelog-rank test was used and Kaplan-Meier plots wereproduced. Hazard ratios (HRs) and associated 95%confidence intervals (CIs) were calculated using Coxregression modeling. The Nelson-Aalen plot was usedto assess the proportional hazards assumption.

Explanation: Give specific details of implementedstatistical analyses.

The principle is to provide “enough detail to enable aknowledgeable reader with access to the original data toverify the reported results” (www.icmje.org).1,35 It is alsoimportant to describe details of who is included in eachstatistical analysis rather than rely on ambiguouslabels such as an intention-to-treat (ITT) analysis.36

Additionally, a clear description of the handling of anymissing data should be provided with clarification ofwhether the analysis followed the per-protocol or theITT principle.36,37 An ITT analysis is one in which allparticipants in a trial are analyzed according to theintervention to which they were allocated, regardlessof whether they received it. ITT is favored inassessments of effectiveness (especially in pragmatictrials) because they mirror the noncompliance andtreatment changes that are likely to occur when theintervention is used in practice, and because of the riskof attrition bias when participants are excluded fromthe analysis. ITT analysis requires participants to beincluded even if they did not fully adhere to theprotocol. An important problem with ITT is missingdata for participants in a clinical trial.

The terminology around ITT analysis is confusingand often interpreted differently by different authors;therefore, a clear delineation of the mechanism of dataanalysis is preferable to a simple statement related toITT or per-protocol analysis or other alternatives suchas treated, available, or consecutive patients. If thereare missing data, any imputations and sensitivity ana-lyses undertaken using plausible scenarios should be re-ported and compared.36,37

In this RCT, methods used for data analysis were out-lined clearly in addition to assessments of the assump-tions underpinning the statistical methods. Handling ofmissing data and sensitivity analyses were also discussed.Secondary analyses for the adhesive remnant index areshown; however, no subgroup analyses were conducted.

Standard methods of analysis assume that the dataare “independent.” For RCTs, this usually means thatthere is 1 observation per participant. Treating multipleobservations from 1 participant as independent data is aserious error; such data are produced when outcomescan be measured on different parts of the body, as indentistry. Data analysis should be based on countingeach participant once or should be done by using morecomplex statistical procedures suitable for noninde-pendent data.13 Empirical evidence has shown that sta-tistical methods are not clearly described and thatobservations that are not independent, such as bondfailures nested within patients, are often inappropriatelytreated as independent observations.38,39

CONSORT item 12b is “methods for additionalanalyses, such as subgroup analyses and adjustedanalyses.”

Example: “Missing outcome data were imputed byusing the variables of intervention type, sex, and age.Imputations were performed under the missing-at-random assumption: ie, assuming that with the givenintervention type, sex, and age, the distribution of

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outcomes was the same whether or not we wereable to observe it. Imputations were implementedusing the “-mi-” family of commands adapted forCox regression. Adhesive remnant index scores be-tween composites were compared by using the Fisherexact test.”

Explanation: It is important to realize that as thenumber of statistical tests conducted increases, thechance of a false-positive result also increases.21

Although multiple subgroup analyses are discouraged,they are common in dental trials40 and may result inselective reporting of “interesting” results and incor-rect interpretations.20 Authors should limit the num-ber of subgroup analyses and should clearly indicatewhether those analyses were prespecified or post hocand exploratory.

RESULTS

Participant flow

CONSORT item 13a is “for each group, numbers ofparticipants who were randomly assigned, receivedintended treatment, and were analyzed for the pri-mary outcome.”

Example: “Figure 1 is an example of a CONSORT flowchart showing the flow of patients through a trial.”

Explanation: The flow diagram is a quick visual aidthat shows the flow of participants through the differentstages of the trial. Any losses to follow-up, balanced orunbalanced, are easily observed as well as the numbersof eligible, randomized, and analyzed patients. Partici-pants assessed for eligibility should also be reported, ifavailable, since it is a useful indicator of whether the trial

Fig 1. Example of a CONSORT flow chart showing patient flow during the trial.

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participants were likely to represent all eligible partici-pants.

CONSORT item 13b is “for each group, losses andexclusions after randomization, with reasons.”

Example: “Two hundred twenty patients (medianage, 16 years; interquartile range, 2 years; range, 12-47 years) were randomized in a 1:1 ratio to either chem-ical or light curing; 16 patients were lost to follow-up(Figs 1 and 2). Patient recruitment commenced in April2009 and ended in November 2010.”

Explanation: Authors should clearly report losses andexclusions after randomization with the reasons. This al-lows assessment of how reasonable were the exclu-sions.41 Additionally, the loss in power from thereduced sample size can also be gauged.

The example RCT includes a flow diagram containingspecific information relating to participant flow and los-ses to follow-up.

Recruitment

CONSORT item 14a is “dates defining the periodsof recruitment and follow-up.”

Example: “Patient recruitment commenced in April2009 and ended in November 2010.”

Explanation: Reporting the timing and the durationof participant recruitment provides historical contextand may be of value to future investigators. In some tri-als, especially in studies assessing time to event out-comes, the length of follow-up is not fixed for allparticipants; rather, follow-up may be ended at a

prespecified time point, perhaps when a fixed numberof outcome events have been observed.

CONSORT item 14b is “why the trial ended or wasstopped.”

Explanation: Results from trials that are completed asplanned are more trustworthy than trials ending prema-turely, especially if the decision was based on examiningthe data. Authors should clearly indicate whether thetrial ended early, including information on the timingand reasons for early termination.

This study did not stop early and contained details ofrecruitment and follow-up.

Baseline data

CONSORT item 15 is “a table showing baseline de-mographic and clinical characteristics for each group.”

Example: “Baseline characteristics of the patients inthe treatment groups are reported in the Table.” (Fig 2is an example of a table reporting baseline characteris-tics.)

Explanation: If randomization has been carried outproperly, treatment groups should be similar in respectof baseline characteristics. Baseline data collected fromall participants may include demographic variables (ie,age, sex, and ethnicity) and clinical characteristicsincluding type of malocclusion, baseline measurementsof crowding, and oral hygiene status. Baseline datashould be collected before random allocation, so thatthe data collection is not influenced by knowledge ofthe treatment allocation. For example, an investigator

Fig 2. Example of a table reporting the baseline characteristics of patients in different treatmentgroups.

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favoring the newer treatment may unconsciously recordbaseline data in a biased manner (eg, round up or downthe amount of crowding) and in a way that would provepreconceptions about the new treatment.

Baseline data displayed in a table allow for quickassessment of similarities between the treatment groupparticipants. Small differences between groups in base-line characteristics are expected due to chance, especiallyin small trials. Large and important differences betweengroup participants at baseline may be associated withimproper randomization.

For continuous variables, such as intermolar width orroot length, means (and standard deviations) or medians(and interquartile ranges) should be included. Variabilityshould not be reported by using standard errors andconfidence intervals because they are inferential andnot descriptive. Variables with a small number of orderedcategories should not be treated as continuous variables;instead, numbers and proportions should be reported foreach category.1 Statistical testing with the objective toassess the balance of baseline characteristics betweentreatment arms is not recommended and is potentiallymisleading.42 It is more sensible that “comparisons atbaseline should be based on consideration of the prog-nostic strength of the variables measured and the sizeof any chance imbalances that have occurred.”2

Numbers analyzed

CONSORT item 16 is “for each group, number ofparticipants (denominator) included in each analysis,and whether the analysis was by original assignedgroups.”

Example: “Two years after entry of the final patient,47 of 110 (42.7%) and 55 of 110 (50.0%) retainersbonded with chemically cured and light-cured adhesiveshad failed, respectively. The primary analysis was carriedout on an intention-to-treat basis involving all patientsrandomized after imputation of missing data.” (Fig 3 isan example of a table reporting the number of failuresand the follow-up period.)

Explanation: The number of participants per groupshould be clear for all analyses. For binary outcomes(ie, risk ratio and risk difference), the denominators orevent rates should also be reported. Expressing resultsas fractions aids the reader in assessing whether somerandomly assigned participants were excluded from theanalysis. It follows that results should not be presentedsolely as summary measures, such as relative risks.

Outcomes and estimation

CONSORT item 17a is “for each primary and sec-ondary outcome, results for each group, and the esti-mated effect size and its precision (such as 95% CI).”

Example: “The hazard ratio (HR) with the imputeddata was 1.15 (95% CI, 0.88-1.70; P 5 0.47). Therewas weak evidence indicating that age might be a signif-icant predictor of lingual retainer failure (HR, 0.96; 95%CI, 0.93-1.00; P 5 0.08). Imputed analysis gave similarHRs with both; the data with no imputations assumedthat all missing observations were censored. Adhesiveremnant index scoring was possible for only 66 of the102 (64.7%) failures and did not differ between compos-ites (Fisher exact test, P5 0.16); most confirmed failuresoccurred at the enamel adhesive level.” (Fig 4 is anexample of a table reporting hazard ratios from Coxregression.)

Explanation: For the primary outcome, authorsshould report the results as a summary of the outcomein each group (eg, the number of participants with orwithout the event, or the means and standard deviationsof the measurements), together with the contrast be-tween groups, known as the effect size. For binary out-comes, the effect size could be the relative risk, relativerisk reduction, odds ratio, or risk difference. For survivaltime data, the measurement could be the hazard ratio ordifference in median survival time. For continuous data,the effect measure is usually the difference in means.Authors should present confidence intervals for thecontrast between groups and as a measure of the preci-sion (uncertainty) of the estimate of the effect. The more

Fig 3. Example of a table reporting the number of failures and the follow-up period.

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clinically relevant and important pieces of informationobtained from the results would be the actual differenceor the effect size and its uncertainty. P values, althoughindicating a statistically significant result, providelimited insight into the clinical relevance of the findings.Reporting confidence intervals moves the interpretationof the results from the dichotomy of significant ornonsignificant to the size of the effect or the associationand its range of plausible values given by the data understudy.1 For paired designs such as split-mouth studies,the within-patient correlation coefficient should be pro-vided to inform future sample calculations.12 Similarly,for designs with clustering effects, the intracluster corre-lation coefficient or the coefficient of variation (k)should be provided.13,43

CONSORT item 17b is “for binary outcomes, pre-sentation of both absolute and relative effect sizes isrecommended.”

Example: “Two years after entry of the final patient,47 of 110 (42.7%) and 55 of 110 (50.0%) retainersbonded with chemically cured and light-cured adhesiveshad failed (risk difference: 7.3%; 95% CI: �5.9%,20.5%), respectively.”

Explanation: Preferably, for binary data, both abso-lute and relative risks should be provided, since an inter-pretation of either in isolation can be misleading.44 Forexample, a small absolute difference of 2 risks (4% �2% 5 2%) equates to a risk ratio of 2 (risk ratio, 4/2 5 2). However, a larger absolute difference betweenrisks (40% � 20%5 20%) may present the same differ-ence in a ratio scale (risk ratio, 40/205 2); interpretationbased on absolute differences (2% vs 20%) may, howev-er, be quite different. Effect estimates in a relative scale,like risk ratios and odds ratios, are more generalizableacross populations than risk differences (difference inproportions), since the latter depend on the baselinerisk of the control group that varies across populations.

Patients were analyzed according to the ITT principleafter missing-data imputations. The estimated hazardratio and the absolute risk difference with associated

95% confidence intervals for the main comparisons areprovided. For the secondary outcome (adhesive remnantindex), the numbers analyzed and the P values are onlyprovided, since only 66% of the failures were examinedfor this outcome.

Ancillary analyses

CONSORT item 18 is “results of any other analysesperformed, including subgroup analyses and adjustedanalyses, distinguishing prespecified from explor-atory.”

Example: “Adhesive remnant index scoring waspossible for only 66 of the 102 (64.7%) failures anddid not differ between composites (Fisher exact test,P 5 0.16); most confirmed failures occurred at theenamel adhesive level.”

Explanation: Participants in clinical trials vary in de-mographic or clinical baseline characteristics, and it ispossible that response to interventions may be influ-enced by baseline characteristics. Subgroup analysesmay be undertaken to identify whether treatment effectsvary across patient groups defined by baseline character-istics such as same sex, age, socioeconomic status, oralhygiene, and cooperation with orthodontic treatment.As the number of analyses increases, so does the proba-bility of observing some false-positive results (multiplic-ity problem).21 Reporting of subgroup comparisonresults may be manipulated, with “interesting” resultsoveremphasized creating false impressions of treatmenteffectiveness; subgroup comparisons should ideally beprespecified.20 Similarly, any adjustments for baselinevariables should preferably be prespecified; it shouldbe stated whether they were carried out as a result ofobserving baseline imbalances.

Harms

CONSORT item 19 is “all important harms or unin-tended effects in each group (for specific guidance,see CONSORT for harms).”

Fig 4. Example of a table reporting hazard ratios from Cox regression.

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Example: “No serious harm was observed other thangingivitis associated with plaque accumulation.”

Explanation: When assessing the evidence for oragainst the effectiveness of an intervention, the balanceof benefits and harms is an important consideration. Aclear description of harms assessed and their frequencyby treatment group should therefore be provided. Anextension of the CONSORT statement on reportingharms in RCTs is available22; in the present trial, noharms other than gingivitis associated with plaque accu-mulation were reported.

DISCUSSION

Limitations

CONSORT item 20 is “trial limitations, addressingsources of potential bias, imprecision, and, if relevant,multiplicity of analyses.”

Example: “Our study's limitation might be that it wasnot possible to examine all patients to inspect the fail-ures, particularly near the end of the study.”

Explanation: In the discussion section, the limita-tions of the trial—particularly potential sources of biases,including measurement bias and attrition bias—shouldbe mentioned. The degree of imprecision of the observedeffect estimates should be discussed with reference tothe reported confidence intervals; emphasis should beplaced on clinical significance rather than P values andstatistical significance.37,44,45

Similarly, greater attention should be given to out-comes from the primary, prespecified analysis; resultsfrom subgroup analyses and after multiple testingshould be interpreted with caution.45,46

Generalizability

CONSORT item 21 is “generalizability (externalvalidity, applicability) of the trial findings.”

Example: “The generalizability of these results mightbe limited because this research was undertaken in asingle center by 1 clinician (N.P.) experienced in bothchemically cured and light-cured bonding.”

Explanation: Applicability of the results of a trial toother settings and populations is often feasible aslong as the trial's inclusion and exclusion criteria aresimilar and under the assumption of consistent bio-logic responses.15,47 For example, would the resultsof an RCT from the United States assessing bondfailures of brackets bonded with self-etching primersor conventional acid etching with only adult subjectsbe applicable to adults in the United Kingdom? Prob-ably yes. Would the same results apply to adolescents?Important differences in cooperation between adultsand adolescents may influence the results; age-

related differences should therefore be consideredwhen assessing external validity.

External validity relies on internal validity; therefore,if trial results are invalid due to biased methods, thequestion of external validity is irrelevant. External valid-ity depends on the setting and the characteristics of thesubjects, interventions, and outcomes of the trial as theyare defined by the inclusion and exclusion criteria.

Interpretation

CONSORT item 22 is “interpretation consistentwith results, balancing benefits and harms, andconsidering other relevant evidence.”

Example: “Although no significant difference inretainer failure rates was noted, the numbers of recordedfailureswere considerable, ranging from43%to 50%overa 2-year period after debonding. This preponderance offailures is compatible with a recent prospective.”

“Our relatively high failure rate.might be related tothe prospective design and the relatively lengthy follow-up. Similarly, any breakage was recorded as such; there-fore, even minor fractures of little consequence, whichmight have been overlooked in other retrospectivestudies, were recorded as failures in this study.”

Explanation: The discussion should consider the ev-idence as a whole, ideally in the context of a systematicreview, rather than focusing on just the current trial oron selected studies, perhaps those that corroborate thetrial results.

This trial discusses the results in the context of theexisting evidence, highlighting the limitations of thestudy and the complexity of achieving prolongedfollow-up, with comments on the generalizability ofthe findings, because the treatment was confined to 1experienced operator.

OTHER INFORMATION

Registration

CONSORT item 23 is “registration number andname of trial registry.”

Example: “This trial was not registered.”Explanation: To minimize the likelihood of nonpu-

blication and data withholding, selective reporting,and duplicate publications, trial registration has beenrequired for publication by the International Committeeof Medical Journal Editors.

This position has resulted in a dramatic increase inthe number of trials that are registered. In an abstract re-porting a trial, the authors should provide details of thetrial registration number and the name of the trial regis-ter.48 This enables readers to obtain more informationabout the trial and its results. Registration information

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also helps to link a report with subsequent full publica-tions (or multiple reports from the same trial) and thusreduces the risk of inadvertent double counting in sys-tematic reviews.

Unregistered trials continue to be published inAJO-DO;this allows for unregistered ongoing trials to be consideredfor publication. At present, the lack of registration willnot preclude publication; the key is that registration orotherwise is transparent. However, this situation is likelyto change in the future; investigators are thereforestrongly encouraged to register trials at the outset(eg, via https://clinicaltrials.gov/).49

Protocol

CONSORT item 24 is “where the full trial protocolcan be accessed, if available.”

Example: “The protocol was not published beforetrial commencement.”

Explanation: Prepublication of the trial protocol isimportant because it gives all the prespecified detailsof the trial. Having the protocol in a public domain al-lows comparisons between what was intended andwhat was actually done, and therefore discourages selec-tive reporting of only “interesting” results.20 Publicationof the protocol also informs the scientific community ofplanned and ongoing trials and allows for bettercommunication and increased efficiency for researchersand systematic reviewers. The SPIRIT guidelines describein detail the requirements for drafting an RCT proto-col.50

Ideally, whether and where the protocol is availableshould be made clear. Transparency is paramount;CONSORT focuses on accurate reporting of what wasdone during the research study without judging this.

Funding

CONSORT item 25 is “sources of funding and othersupport (ie, supply of drugs), and the role of funders.”

Example: “No funding or conflict of interest isdeclared.”

Explanation: Funding and other forms of supportshould be declared explicitly. It has been shown that tri-als sponsored by the pharmaceutical industry havehigher odds of having outcomes favoring the sponsorthan do studies funded by other sources.51 Typically,sources of funding are reported at the end of the abstractor in the “acknowledgments” section of the article.

ABSTRACT

In the final section of this explanatory article, weaddress how to report the abstract of a randomized trial,following CONSORT for abstracts guidelines.3 These

items have all been described above; however, a shortdescription is necessary, since orthodontic abstracts areoften reported incompletely.6

The checklist for what to include in the abstract isshown in Table II. The key points are as follows.

1. An important reason for clarifying the trial design isto ensure appropriate indexing in electronic data-bases, ensuring greater ease of identification.

Example: “2-arm parallel trial.”

2. Clear descriptions of the trial participants and thesetting in which they were studied are needed sothat readers can assess the external validity (gener-alizability) of the trial and determine the applica-bility to their own setting.

Example: “Eligibility criteria included no activecaries, restorations, or fractures in the mandibularanterior teeth, and adequate oral hygiene.”

3. The essential features of each experimental andcomparison intervention should be described.

Example: “Patients having undergone orthodontictreatment at a private orthodontic office were ran-domly allocated to fixed retainers placed with chem-ically cured composite or light-cured composite.”

4. The abstract should provide a clear statement of thespecific objective or hypothesis addressed in the trial.

Example: “The objective of this trial was to comparethe survival rates of mandibular lingual retainersbonded with either a chemically cured or a light-cured adhesive after orthodontic treatment.”

5. The authors should explicitly state the primaryoutcome for the trial and when it was assessed(eg, the time frame over which it was measured).

Example: “The main outcome was any type of first-time lingual retainer breakage; pattern of failure(adapted adhesive remnant index scores) was a sec-ondary outcome. Patients were reviewed at 1, 3, and6 months and then every 6 months after placementof the retainer until completion of the study.”

6. It is important to give details of the randomsequence generation method, the randomizationmethod, and the restrictions implemented, andalso of the concealment of the allocation sequencefrom those assigning participants to the inter-vention groups. Allocation concealment prevents

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investigators from influencing which participantsare assigned to an intervention group (ie, selectionbias).

Example: “Randomization was accomplished withrandom permuted blocks of 20 patients with the al-locations concealed in sequentially numbered, opa-que, sealed envelopes.”

7. Authors should clarify whether the participants,those administering the intervention (usually healthcare providers), and those assessing the outcome(data collectors and analysts) were blinded to thegroup allocation.

Example: “Blinding was applicable for the outcomeassessment only.”

8. The number of participants randomized to eachintervention group should be explicit because it isan essential element of the results of a trial. Thisnumber defines the sample size, and readers canuse it to assess whether all randomized participantswere included in the data analysis.

Example: “Two hundred twenty patients (medianage, 16 years; interquartile range, 2 years; range,12-47 years) were randomized in a 1:1 ratio toeither chemical or light curing.”

9. For the primary outcome, the authors should reportthe results as a summary of the outcome in eachgroup (eg, the number of participants with orwithout the event, or the means and standard devi-ations of the measurements), together with the con-trasts between the groups, known as the effect size.For binary outcomes, the effect size could be relativerisk, relative risk reduction, odds ratio, or risk differ-ence. For survival time data, the measurement couldbe the hazard ratio or the difference in median sur-vival times. For continuous data, the effect measureis usually the difference in means. Authors shouldpresent confidence intervals for the contrasts be-tween groups and as a measure of the precision (un-certainty) of the estimate of the effect.

Example: “At aminimum follow-up of 2 years, 47 of110 (42.7%) and 55 of 110 (50.0%) retainers hadsome type of failure with chemically cured andlight-cured adhesives, respectively (log-rank test,P 5 0.35). Data were analyzed on an intention-to-treat basis, and the hazard ratio (HR) was 1.15(95% CI, 0.88-1.70; P 5 0.47). There was weak

evidence that age is a significant predictor forlingual retainer failures (HR, 0.96; 95% CI, 0.93-1.00; P 5 0.08). Adhesive remnant index scoringwas possible for only 66 of the 102 (64.7%) failuresand did not differ between composites (Fisherexact test, P 5 0.16).”

10. Tomake balanced decisions, readers need informa-tion about the relative benefits and harms of anintervention. Important adverse (or unexpected)effects of an intervention should be alluded to inthe abstract. If no important adverse events haveoccurred, the authors should state this explicitly.

Example: “No serious harm was observed otherthan gingivitis associated with plaque accumula-tion.”

11. The conclusions of the trial, consistent with the re-sults reported in the abstract, should be clearlystated along with their clinical applications (avoid-ing generalizations). When applicable, authorsshould also note whether additional studies arerequired before the results are used in clinicalsettings.

Example: “The results of this study indicated noevidence that survival of mandibular lingual re-tainers differs between chemically and light-curedadhesives. The overall failure rate was 46.4%; how-ever, this included any type of failure, which couldhave exaggerated the overall failure rate.”

12. Registration of the trial and the details of theresearch protocol, although not a CONSORT state-ment item, and funding should be documented.

Examples: “This trial was not registered,” “theprotocol was not published before trial commence-ment,” or “no funding or conflict of interest isdeclared.”

CONCLUSIONS

When making clinical decisions, the evidence-baseddentistry approach amalgamates the best available evi-dence, clinical expertise, and patients' preferences andvalues. High-quality RCTs form the backbone of system-atic reviews, which should be at the forefront ofevidence-based decision-making. Complete and trans-parent trial reporting facilitates accurate assessment ofthe quality of the study and correct interpretation ofthe results. Moreover, identification of studies suitable

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for inclusion in systematic reviews, appraisal of primarystudies, and data extraction are expedited by clear re-porting. Empirical evidence has shown that reportingof RCTs in medicine and dentistry remains suboptimaland is compromised by failure to publish, and by incom-plete, selective, and misleading reporting. The CONSORTguidelines provide influential and important answers tothese problems, and should be adhered to when report-ing clinical trials in orthodontics. They can also informthe design and conduct of trials.

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