the prevalence of common skin conditions in australian school students: 3. acne vulgaris

The prevalence of common skin conditions in Australianschool students: 3. Acne vulgaris

M.KILKENNY, K.MERLIN, A.PLUNKETT AND R.MARKSThe University of Melbourne, Department of Medicine (Dermatology), St Vincent’s Hospital, Fitzroy 3065, Victoria, Australia

Accepted for publication 15 June 1998

Summary The prevalence, severity and disability related to facial acne (comprising acne on the head and neck)was assessed in a randomized sample of 2491 students (aged 4–18 years) from schools throughoutthe State of Victoria in Australia. Students were diagnosed clinically by a dermatologist ordermatology registrar. The overall prevalence (including 4–7 year olds) was 36·1% (95% confidenceintervals, CI 24·7–47·5), ranging from 27·7% (95% CI 20·6–34·8) in 10–12 year olds to 93·3%(95% CI 89·6–96·9) in 16–18 year olds. It was less prevalent among boys aged 10–12 years thangirls of the same age; however, between the ages of 16 and 18 years, boys were more likely than girlsto have acne. Moderate to severe acne was present in 17% of students (24% boys, 11% girls).Comedones, papules and pustules were the most common manifestations of acne, with one in fourstudents aged 16–18 years having acne scars. Twelve per cent of students reported a high AcneDisability Index score. This tended to correlate with clinical severity, although there was someindividual variation in perception of disability. Seventy per cent of those found to have acne onexamination had indicated in the questionnaire that they had acne. Of those, 65% had soughttreatment, a substantial proportion of which (varying with who gave the advice) was classified asbeing likely to have no beneficial effect. This is the first population-based prevalence study onclinically confirmed acne published from Australia. The results show that acne is a common problem.They suggest the need for education programmes in schools to ensure that adolescents understandtheir disease, and know what treatments are available and from whom they should seek advice.

Acne vulgaris is a common skin condition whichusually begins in adolescence and often resolves onceearly adulthood is reached. In studies on the prevalenceof acne in schoolchildren, the frequency has varied from30 to 100%.1–4 The Victorian Adolescent HealthSurvey recorded the frequency of self-reported acne in2491 school students in 1992, and showed an associa-tion between the frequency and severity of self-reportedacne and stage of pubertal development.5 To date, therehave been no population-based prevalence studies onclinically confirmed acne in Australia. Although con-sidered trivial by many, these data are important inquantifying disability, cost and use of health services.They can also be used as a guide to whether there is aneed for the education of those affected and those whoprovide care for them.

This paper reports the prevalence and severity of facialacne (comprising the head and neck) in a representativesample of students in schools in Victoria, Australia. Inaddition, information was collected with regard to

whether treatment had been sought for acne and fromwhom. A sample of students completed an Acne Disabil-ity Index (ADI) to assess what impact acne had on theirlives.6 The survey also recorded the prevalence of atopiceczema, viral warts and tinea pedis in the schoolchildren:these are the subjects of other reports.7

Subjects and methods

School skin survey

The school skin survey collected information on theprevalence of common skin conditions in Australianschool students. The sample was a stratified two-stageprobability sample. The three strata covered Govern-ment, Independent and Catholic schools in the State ofVictoria. A detailed procedure for recruitment of schoolswas undertaken to ensure maximum participation.More details of the sampling and recruitment under-taken for this survey are summarized in a previouspublication.7

British Journal of Dermatology 1998; 139: 840–845.

840 q 1998 British Association of Dermatologists

Correspondence: Professor R.Marks.

Data collection

Prior to examination, parents and students filled out aquestionnaire on country and date of birth, sex, perso-nal history of skin disease (including a direct questionasking whether they suffered from ‘acne/pimples at themoment’), whether treatment had been used and fromwhom advice had been sought. A senior dermatologistclassified any product reported to have been used aslikely to be efficacious or not on the basis of currentdermatological practice. Where there was insufficientinformation to be absolutely clear whether the productwas likely to be effective or not, it was given the benefitof the doubt and classed as efficacious.

On the examination day, schools were visited by a teamcomprising a consultant dermatologist, dermatologyregistrar, nurse, project manager and project co-ordina-tor. Examiners recorded on the data collection sheet thenumber and type of acne lesions present. Severity wasalso assessed globally by the examiners and classified asminimal, mild, moderate and severe. The examinationfor acne included the head and neck only. It is recognizedthat other areas of the body are susceptible to acne,especially the trunk. As this survey was purely voluntary,requiring parental and student consent, we believed thatthe request for a full body examination would havesubstantially lowered the participation rate, particularlyamong adolescents.

Diagnostic definition

Clinical diagnosis was used for recording the frequencyof acne. Lesions recorded included comedones, papulesor pustules, postinflammatory pigmentation, cysts ornodules and acne scars. The definition of severity wasleft to the examiners taking into account the numberand extent of comedones, inflammatory lesions,nodules, cysts and scarring, as well as requirementfor treatment. For example, <50 comedones plus oneto five small inflammatory papules only would beclassified as minimal, and many cysts and nodulesassociated with scarring would be classified as severe.Mild and moderate were intermediate categories.Because of the limited time available in the largenumber of examinations, the examiners were giventhe flexibility to decide the severity grading at the timerather than relying on a complicated scoring systemcalculated later. Their interobserver variation wasthen assessed for concordance. In order to assessinterobserver variation, every 17th student (6% ofthe total study sample) was selected to have twoexaminations, one each by two different examiners.

The results were assessed for interobserver agreementon both diagnosis of acne lesions and assessment ofseverity.

Data analysis

Data collected from students were entered and verifiedon a relational database (FileMaker Pro Version 4·0).8

The Statistical Package for Social Sciences (SPSS Ver-sion 6·1) was used for analysis.9 Prevalence estimateswere expressed in terms of prevalence rates with 95%exact confidence intervals (CI). Interobserver agreementwas assessed using the Kappa statistic for categoricalvariables to compare pairs of examiners.

Acne Disability Index

A sample of secondary school students completed a self-reported ADI assessment.6 They comprised the last 382students seen consecutively in the survey. Answers toeach of the five questions in the ADI were scored and atotal score for the index calculated for each student. Thefive questions relate to feelings of aggression, frustra-tion, interference with social life, avoidance of publicchanging facilities, and appearance of the skin—allover the last month—and an indication of how badthe acne is now. ADI scores were graded as low (0–4)and medium to high (5–15). The lower the cumulativeADI score, the lower the level of disability experienced bythe student; a higher score indicated a higher level ofdisability. The degree of acne severity as determined bydermatological examination was then compared withthe level of disability reported on the ADI.

Results

Population sample

In total, 2491 students (64%) were examined from theoriginal sample of 3871 students selected for examina-tion. They comprised 1174 boys and 1317 girls. Com-parison of gender, type of school and age of the studentswho would not be examined with those who would,revealed no statistical difference between the two popu-lations. Similarly, comparison of completed question-naire data for those students who were not examined(179 completed questionnaires) with those who were,revealed no differences between the two groups.7 Thisincluded a self-report of presence of acne (28% forstudents examined and 29% for those not examined).

ACNE IN AUSTRALIAN SCHOOLCHILDREN 841

q 1998 British Association of Dermatologists, British Journal of Dermatology, 139, 840–845

Interobserver variation

In general, the interobserver agreement for diagnosisand assessment of severity was good (Table 1). Althoughpositive agreement between observers was very high for‘cysts/nodules’ and ‘postinflammatory pigmentation’,the Kappa statistic was low. There were relativelysmall numbers on which the Kappa statistics werebased in these two categories.

Prevalence of acne

Overall, the prevalence of facial acne in the age range4–18 years (adjusted for the age and sex distribution ofthe total school student population in Victoria) was36·1% (95% CI 24·7–47·5). It was more common ingirls (41%) than boys (31%). The prevalence increasedwith age, and was substantially less common amongyounger boys than girls (Table 2). In the 10–12 yearage group, only 15% of boys compared with 41% of girlshad facial acne. The sex difference in acne prevalence

was negligible between ages 13 and 15. Between theages of 16 and 18, boys were more likely than girls to beaffected.

Of the 706 students who reported on their ques-tionnaire that they had acne, 615 (87%) had thisconfirmed by clinical examination. Only 615 (70%) ofthe 873 students who had acne on examination hadreported on the questionnaire that they had acne(Table 3). Thus, the sensitivity for parent or studentawareness of their acne was 70%, the specificity was94% (1527 of the 1618 students who did not haveacne correctly reported on the questionnaire that theydid not have acne) and the positive predictive valuewas 87%. There was an increase with age in all of themanifestations of acne recorded in the study (Table 4).Comedones were the most common type of lesionfollowed by papules/pustules, acne scars, cysts/nodules and postinflammatory pigmentation. One infour students in the age group 16–18 years had someacne scarring.

842 M.KILKENNY et al


Table 1. Interobserver agreement for diagnosis and of severity of acne in the 143 students who were examined by two observers

Prevalence (%) Positive agreement (%)a (no. agreed cases) Kappa statistic

Presence of acneb 36 90 (128) 0·78Acne lesionsb

Comedones 33 90 (128) 0·77Papules/pustules 29 85 (122) 0·66Cysts/nodules 1 99 (141) 0·49Postinflammatory pigmentation 7 91 (130) 0·27Acne scars 6 97 (139) 0·70SeverityMinimal 14 83 (118) 0·36Mild 15 86 (123) 0·53Moderate to severe 6 94 (135) 0·47

a Positive agreement means the proportion of all positive responses between paired investigators where both observers were in perfect agreement.b Rates adjusted for the age and sex distribution of the total school student population in Victoria.

Table 2. Overall prevalence of acne of head and neck by age and sex (no acne was recorded in children aged 4–6 years)

Overall Boys Girls

Age groups (years) Prevalence % (no. cases) 95% CI Prevalence % (no. cases) 95% CI Prevalence % (no. cases) 95% CI

7–9 3·0 (19) 1·5–4·6 1·8 (6) 0·4–3·2 4·3 (13) 1·9–6·810–12 27·7 (188) 20·6–34·8 14·9 (48) 9·1–20·7 40·7 (140) 31·4–50·113–15 78·2 (418) 73·8–82·6 77·4 (194) 71·3–83·5 78·9 (224) 72·8–85·116–18 93·3 (248) 89·6–96·9 97·8 (114) 94·8–100·0 89·8 (134) 83·0–96·5Total (4–18) 36·1 (873) 24·7–47·5 30·7 (362) 19·2–42·3 41·2 (511) 29·1–53·3

CI, confidence intervals. Rates and CI adjusted for the age and sex distribution of the total school student population in Victoria.

Severity of facial acne

Moderate to severe facial acne was present in 17% ofstudents, being more common in boys than girls (Table5). The proportion with more severe disease increasedwith age. Among boys, the proportion with moderate tosevere acne increased from 2% at 10–12 years to 30%at 16–18 years. Among girls, the proportion with mod-erate to severe acne increased from 3% at 10 to 12 yearsto 19% at 16–18 years.

Acne Disability Index

Of the 267 students who completed the ADI and whowere diagnosed clinically with acne, 223 (84%) had ascore of 0–4, 37 (14%) had a score of 5–9 and seven(3%) had a score of 10–15. Specific responses included44% of students reporting that they felt aggressive,frustrated or embarrassed as a result of having acne/pimples. Almost 25% of students reported that havingacne/pimples interfered with their daily social life, socialevents or relationships with members of the oppositesex. Fewer than 8% of students avoided public changingfacilities or wearing swimming costumes, although 62%did register some concern about the appearance of theirskin. Of those who perceived their acne/pimples to be aproblem, 55% classified their problem as minor, 11% asmajor and 1% as ‘the worst it could possibly be’.

Relationship between clinical severity and Acne DisabilityIndex score

In general, there was a linear relationship between self-reported disability and acne severity recorded on clinicalexamination (Fig. 1). However, the SD of the mean ADIscores was relatively wide for the mild to moderateclassifications, indicating variation in the individualperception of the effect of the disease. For example,there were students who had a moderate ADI scorewith clinically mild disease and vice versa.

Treatment for acne

Of the 615 students found to have acne on examination,and who had reported on the questionnaire that theyhad acne, 397 (65%) had used one or more products totreat their condition. Family and friends and othersources (e.g. media, beautician, alternative practitioner)were the sources of advice on treatment. A total of 525products had been used. Many were general (non-specific) products (46%) rather than specific over-the-counter (40%) or prescription products (10%) for acnepurchased from a pharmacy. Examples of general pro-ducts included cleansers, soaps, facial scrubs andmasks. When coded by the senior dermatologist asefficacious or non-efficacious according to producttype, 18% of products recommended by a medicalpractitioner were likely to have no beneficial effect onacne. On the other hand, 49% of products recom-mended by a pharmacist and 75% of products recom-mended by family and friends were likely to have nobeneficial effect. Only 52% of the products reported tohave been used by students with moderate to severeacne were classified as likely to have any beneficial effecton the disease.

Discussion

This is the first population-based study completed in



Table 3. A comparison of the responses on the questionnaire towhether or not acne was present with the findings on cutaneousexamination

Examination

Acne No acne

Questionnaire Acne 615 91No acne 258 1527

Table 4. Prevalence of the different components of acne by age (no acne was recorded in children aged 4–6 years)

Age groups Students Comedones % Papules or pustules % Postinflammatory Cysts or nodules % Acne scars %(years) examined (95% CI) (95% CI) pigmentation % (95% CI) (95% CI) (95% CI)

7–9 665 2·0 (0·8–3·1) 1·8 (0·3–3·3) 0 (0) 0 (0) 0 (0)10–12 636 25·2 (18·8–31·5) 19·9 (13·6–26·2) 0·2 (0·5–2·8) 1·7 (0–1·0)a 1·2 (0·4–2·1)13–15 539 69·7 (62·9–76·5) 64·7 (58·3–71·0) 2·3 (10·1–22·0) 16·0 (0·6–4·0) 11·6 (7·5–15·7)16–18 266 87 (81·7–92·6) 80·7 (74·6–86·9) 3·6 (15·8–35·3) 25·6 (1·8–5·3) 26·1 (19·1–33·1)

CI, confidence intervals. aIn this group, where the number of cases was small, the lower confidence interval falls below zero as a statistical artefact ofthe formula used to calculate the CI. In this case, the lower limit has been recorded as zero.

Australia which outlines in detail the prevalence of acnein school students. It showed that it is common, varyingfrom 28% in 10–12 year olds to 93% in 16–18 yearolds. A shortcoming in this study is that examinationdid not include the trunk, another important site foracne. Thus, what proportion of students with acne havewe missed, i.e. what proportion of students would havetruncal acne in the absence of any sign of acne on thehead and neck, including comedones? It has beensuggested that this is likely to be considerably lessthan 5%.10 Although it means that we may be under-reporting the true prevalence of acne overall, it is notlikely to be by a large amount.

The estimate of frequency of acne and its severitydepends on the diagnostic criteria used and how it isgraded. There is no widely accepted standard classifica-tion system. For this reason, we believe that it was best

to report all the manifestations of acne from comedonesto nodules and cysts, not only by presence but alsonumber. We then reported a person as having acne ifthey had one or more of these components. Havingrecorded the type and number of lesions, the examinerswere then asked to give a global assessment of severity.Once again, there is no internationally agreed systemfor reporting severity, although various systems havebeen recommended.11–13 Nevertheless, in our com-parison of reporting between examiners, we had goodagreement for both presence of the various manifesta-tions of acne and also the severity. It is clear that indermatoepidemiology there is a need to develop a uni-versal, standardized acne classification system for use inboth descriptive studies and clinical trials.

Our study fits well with the previous findings thatgirls have an earlier onset of acne than boys, reflectingthe earlier onset of puberty in girls.1 A study of 8298students in Sweden found that 37% of girls had acne atage 12 years compared with 15% of boys.2 Our studyalso concurs with others that showed that boys tend tohave a higher prevalence of the disease late in adoles-cence compared with girls. The same applies to theseverity of acne in older adolescents, with 30% of boyshaving moderate to severe acne compared with 19% ofgirls.1–3 The ADI, previously reported to be useful inmeasuring the impact of acne on students, demon-strated a fairly good correlation between acne severityand reported disability in our study. However, it was notabsolute and there was some variation between thedegree of severity reported by the students and whatwas found on clinical examination, particularly withthose students with mild to moderate acne. It highlightsthe subjective nature of the ADI. It indicates also a needto be aware that sensitivity about disease on the facemay be presenting problems to the adolescent wellbeyond what they may seem clinically to the attendingmedical practitioner.

844 M.KILKENNY et al


Table 5. Severity of acne by sex and age groups

Students with acne Minimal (%) Mild (%) Moderate to severe (%)

Overall 873 40 43 17Boys 362 34 42 24Girls 511 45 44 11Age groups (years)

7–9 19 95 5 010–12 188 60 38 313–15 418 37 44 1916–18 248 27 49 24

Figure 1. Acne Disability Index (ADI) scores in relation to severity in267 students with acne. The maximum possible ADI score is 15.

The prevalence of moderate to severe acne in theolder adolescents was high despite a wide range ofadequate treatment being readily available in Australia.Even when students had sought treatment, the productsreported in the questionnaire were frequently classifiedas having no therapeutic value. A large proportion hadnot sought advice from someone who may be in aposition to help, for example, a medical practitioner ora pharmacist. Most had sought advice from their familyand friends or other sources such as the media, beau-ticians or alternative practitioners. There is a need forfurther education, both public and within schools,about the nature of acne and where to seek advicewhich may be of value.

In summary, this study has shown that acne iscommon in Australian school students. The prevalenceof acne increased with age, with virtually every adoles-cent being affected at some stage during puberty.Further work is necessary to ensure that those affectedhave access to the readily available treatment which hasthe potential not only to treat the disease present todaybut also to prevent the scarring, both physical andemotional, which may result in the long term.

Acknowledgments

The authors acknowledge the help of Dr JosephineYeatman, Mr Damien Jolley, Dr Yeqin Zuo and DrMalcolm Rosier in the design and analysis of thestudy. Dr David Gill, Dr Richard Young and Ms VoulaStathakis assisted on the examination days at schools.We also thank Ms Val Bennett, the project nurse and DrsTanja Bohl, Barbara Breadon, Carol Burford, AnnetteCallen, Anthony Hall, Anne Howard, Michael Lee,Adrian Mar, Rod Sinclair and Craig Smith. Professor

W.J.Cunliffe, Leeds, U.K., gave useful advice on gradingthe disease. This work was supported by grants from theAustralasian College of Dermatologists; the Skin &Cancer Foundation, the F.Bauer Foundation, the JackBrockhoff Foundation (Victoria) and the WilliamAngliss Trust (Victoria).

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the prevalence of common skin conditions in australian school students: 3. acne vulgaris

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