how to write a clinical article
TRANSCRIPT
Dr Arjun Rajagopalan
Writing a paper
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
STEP 1
The need
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
"If$you$don't$have$0me$to$read,$you$don't$have$the$0me$4$or$the$tools$4$to$write.$Simple$as$that."$
Stephen$King
Dr Arjun Rajagopalan
With%reference%to%Problem%“X”%the%unresolved%
issue(s)%at%stake%is:%Lorem%ipsum%dolor%sit%amet,%
consectetur%adipiscing%elit%…
The%grand%unifying%
model%of%
introduc,onsKnowledge spectrum
Ignorance Clarity
We%are%
now%here
Our%study%will%shiQ%
this%posi,on%….
Dr Arjun Rajagopalan
STEP 2
Asking an answerable question
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
The%4%part%ques,on
Popula,on
Indicator%variable
Outcome%variable
Comparison
An0bio0c$prophylaxis$at$urinary$catheter$removal$prevents$urinary$tract$infec0ons%Annals&of&Surgery&2009;&249:573–575
Popula0on Pa0ents$undergoing$elec0ve$abdominal$surgery$at$a$single$centre$with$planned$periopera0ve$urethral$catheteriza0on$
Indicator$variable
Three$doses$of$trimethoprim4sulfamethoxazole$at$urinary$catheter$removal.
Outcome$variable
Primary:$occurrence$of$urinary$tract$infec0on$aGer$catheter$removal.$Secondary:$occurrence$of$asymptoma0c$bacteruria.$
Comparison No$an0bio0c$prophylaxis.
Dr Arjun Rajagopalan
The%prac,ce%of%
Medicine
Tag%the%ar,cle
$
$$
Observa,on
MeasurementInterven,on
Outcome
Cure%%%%%%%%%Death
Dr Arjun Rajagopalan
Tag%the%ar,cle
$
$$
Observa,onal
PATTERNS%
Causa,on%
Epidemiology
Diagnos,c%efficacy%
Decision%making%in%states%of%
uncertainty
Interven,onal
Alter%outcome
DIFFERENCES$Odds/%risk/%associa,on%
Clinical%trials
TITLE TYPE/%TAG
Readmission%aQer%colectomy%for%cancer%
predicts%one>year%mortality
An,bio,c%prophylaxis%at%urinary%catheter%
removal%prevents%urinary%tract%infec,ons
CA19>9%serum%levels%in%obstruc,ve%
jaundice:%clinical%value%in%benign%and%
malignant%condi,ons
Observa,onal
Interven,onal
Diagnosis
Be%wary%of%ar,cles%that%a6empt%to%be%%
more%than%one%of%the%three%types
Dr Arjun Rajagopalan
STEP 3
Materials & Method
Dr Arjun Rajagopalan
The%prac,ce%of%
Medicine
$
$$
Observa,on%
(Popula,on)
MeasurementInterven,on
Outcome
Cure%%%%%%%%%Death
Dr Arjun Rajagopalan
STEP 3 AMaterials & Method
POPULATION(The sample)
Dr Arjun Rajagopalan
Clearly%state%this%
dis,nc,on
Random
Epidemiological$studies
Non>random
Clinical%studies
Dr Arjun Rajagopalan
The%value%chain
Non>random
Type Choice%of%individuals%from%available%
candidates
Consecu,ve All$available
Convenience Easily$available
Judgmental Hand$picked
Where%do%you%lie%in%
this%chain%of%value?
Dr Arjun Rajagopalan
Points%of%error%in%the%
sampling%process
The%“universe”$Rarely%accessible
Accessible%popula,on
Demographical$Socio>economic$
TemporalRecruitm
entIntended%popula,on
Inclusion$Exclusion
Study%popula,onDrop%outs$
(>15%%=%invalid)
Tranexamic$Acid$Treatment$for$Heavy$Menstrual$Bleed$Lukes$AS,$Moore$KA,$Muse$KN,$et$al$Obstet$Gynecol$2010;116:865–75
?%Target% Accessible
Intended
Study
711
196
123 73
115 72
An%example
Dr Arjun Rajagopalan
THIS%STUDYWith%
prophylaxis
Without%
prophylaxis
TARGET%POPULATION ?
ACCESSIBLE%POPULATION ?%PATIENTS
INTENDED%POPULATION 119 120
STUDY%POPULATION 103 102
Dr Arjun Rajagopalan
How%much%is%
enough?
The%“power”%of%a%
sample
A%priori%sample%size%
determina,on
Postulated%size%of%difference%between%groups
Power%of%the%test%to%detect%this%difference%–%as%%%>%(usually%
80>90%)
Acceptable%margin%of%error%(as%a%decimal)
An0bio0c$Prophylaxis$at$Urinary$Catheter$Removal$Prevents$Urinary$Tract$Infec0ons$$Pfefferkorn$U,$$Lea$$S,$MD,$$Moldenhauer$J,$et$al$Ann$Surg$2009;249:$573–575$
The$sample$size$was$determined$assuming$a$rate$of$urinary$tract$infec0ons$of$5%$in$the$group$with$an0bio0c$prophylaxis$and$of$15%$in$the$group$without$prophylaxis.$To$detect$a$10%$difference$with$a$significance$level$of$0.05$and$sta0s0cal$power$of$80%,$a$total$of$220$pa0ents$were$required.
Dr Arjun Rajagopalan
STEP 3 BMaterials & Method
INTERVENTION& COMPARISON
Dr Arjun Rajagopalan
Apples%vs%...?
The%act%of%
comparing
Design%of%interven,onal%trials
Interven,on%“A”
Outcome%“A”
Interven,on%“B”
Outcome%“B”
Conclusion:%“There%is%a%difference%between%“A”%and%“B”
Dr Arjun Rajagopalan
2%cri,cal%ques,ons%in%interven,onal%trials
?Is%there%a%
comparison?$Study%vs%control
Is%the%
comparison%fair?
Prospec,ve Retrospec,ve
Randomized%controlled$trial%(RCT)
%>%Case>controlled$>%Case%series
Assuring%comparable%groups:%$
The%randomized%controlled%trial%(RCT)
Inclusion$Exclusion
Accessible$popula,on
Intended$popula,on
Random%
alloca,on
Control$group
Study$group
Outcome Outcome
“There%is/%isn’t%a%difference
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Comparable%groups
An0bio0c$Prophylaxis$at$Urinary$Catheter$Removal$Prevents$Urinary$Tract$
Infec0ons$$Pfefferkorn$U,$$Lea$$S,$MD,$$
Moldenhauer$J,$et$al$Ann$Surg$2009;249:$573–575
Assembling%comparable%groups:%$
The%case>controlled%trial
Inclusion$Exclusion
Accessible$popula,on
Intended$popula,on
Control$group
Study$group
Outcome Outcome
“There%is/%isn’t%a%difference
One>to>one%(n)%
match%except%
for%indicator%
variable
Assembling%comparable%groups:%$
Retrospec,ve%(historical)%controls
Inclusion$Exclusion
Accessible$popula,on
Intended$popula,on
Control$group
Study$group
Outcome Outcome
“There%is/%isn’t%a%difference
Retrospec,ve$Not%matched
Dr Arjun Rajagopalan
Variability%in%
the%
interven,on
Standardizing%
interven,ons
Protocols
Training
Skill stratification
Blinding
Dr Arjun Rajagopalan
STEP 3 CMaterials & Method
MEASUREMENT
Dr Arjun Rajagopalan
Measurement%error
Measurement$error
OBSERVER%ERROR DEVICE%ERROR
Dr Arjun Rajagopalan
Keeping%it%
down
Protocols
Training
Repetition
Multiple observers
Blinding
Minimizing$observer$error
OBSERVER%ERROR
Dr Arjun Rajagopalan
Measuring%
observer%error
Intra>observer Inter>observer
Kappa$Value$(0%–%1)
Dr Arjun Rajagopalan
Keeping%it%
down
DEVICE%ERROR
Minimizing$device$error
Protocols
Repetition
Appropriateness
“Gold standard” comparisons
Dr Arjun Rajagopalan
STEP 4Results
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
STEP 5Statistical analysis
Dr Arjun Rajagopalan
Is%this%difference%real%or%due%to%chance?
Chances%are%...
Dr Arjun Rajagopalan
Chances%are%...
Familiarity with medical statistics leads inevitably to the conclusion
that common sense is not enough… Many people are not
capable of using common sense in the handling and interpretation of numerical data until they have
been instructed
Sir Austin Bradford Hill
Dr Arjun Rajagopalan
Biosta,s,cs%
demys,fied:%two%
keys%to%
understanding%
the%mystery
“Black%box”%
Biosta,s,cal%mumbo>jumbo
2%es,mates%of%chance
95%%(CI)$(confidence%interval) ‘p’%value
Is%it%true?%
Yes/NoWhere%is%the%truth?%
Show%me%the%money
Dr Arjun Rajagopalan
STEP 6Conclusion
Dr Arjun Rajagopalan
The%4%part%ques,on
Popula,on
Indicator%variable
Outcome%variable
Comparison
Dr Arjun Rajagopalan
STEP 7Discussion
Dr Arjun Rajagopalan
With%reference%to%Problem%“X”%the%unresolved%
issue(s)%at%stake%is:%Lorem%ipsum%dolor%sit%amet,%
consectetur%adipiscing%elit%…
Knowledge spectrum
Ignorance Clarity
We%are%
now%here
Our%study%will%shiQ%
this%posi,on%….
Drawbacks%
Strengths%
Contribu,on
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
STEP 8The manuscript
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
INSTRUCTIONSTO
AUTHORS
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
First language
5%Fluent
speakers 4%
Non-English Speakers 91%
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Dr Arjun Rajagopalan
Evidence Based Medicine
The Evidence PyramidAb
ility t
o co
ntro
l bias
and
dem
onst
rate
caus
e and
effec
t
Dr Arjun Rajagopalan
THAN
K%YOU