how to write a clinical article

Dr Arjun Rajagopalan

Writing a paper


STEP 1

The need


"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


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%….


STEP 2

Asking an answerable question


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.


The%prac,ce%of%

Medicine

Tag%the%ar,cle

$

$$

Observa,on

MeasurementInterven,on

Outcome

Cure%%%%%%%%%Death


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


STEP 3

Materials & Method


The%prac,ce%of%

Medicine

$

$$

Observa,on%

(Popula,on)

MeasurementInterven,on

Outcome

Cure%%%%%%%%%Death


STEP 3 AMaterials & Method

POPULATION(The sample)


Clearly%state%this%

dis,nc,on

Random

Epidemiological$studies

Non>random

Clinical%studies


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?


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


THIS%STUDYWith%

prophylaxis

Without%

prophylaxis

TARGET%POPULATION ?

ACCESSIBLE%POPULATION ?%PATIENTS

INTENDED%POPULATION 119 120

STUDY%POPULATION 103 102


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.


STEP 3 BMaterials & Method

INTERVENTION& COMPARISON


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”


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


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


Intended$popula,on

Control$group

Study$group

Outcome Outcome


One>to>one%(n)%

match%except%

for%indicator%

variable

Assembling%comparable%groups:%$

Retrospec,ve%(historical)%controls

Inclusion$Exclusion


Intended$popula,on

Control$group

Study$group

Outcome Outcome


Retrospec,ve$Not%matched


Variability%in%

the%

interven,on

Standardizing%

interven,ons

Protocols

Training

Skill stratification

Blinding


STEP 3 CMaterials & Method

MEASUREMENT


Measurement%error

Measurement$error

OBSERVER%ERROR DEVICE%ERROR


Keeping%it%

down

Protocols

Training

Repetition

Multiple observers

Blinding

Minimizing$observer$error

OBSERVER%ERROR


Measuring%

observer%error

Intra>observer Inter>observer

Kappa$Value$(0%–%1)


Keeping%it%

down

DEVICE%ERROR

Minimizing$device$error

Protocols

Repetition

Appropriateness

“Gold standard” comparisons


STEP 4Results


STEP 5Statistical analysis


Is%this%difference%real%or%due%to%chance?

Chances%are%...


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


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


STEP 6Conclusion


The%4%part%ques,on

Popula,on

Indicator%variable

Outcome%variable

Comparison


STEP 7Discussion


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


STEP 8The manuscript


INSTRUCTIONSTO

AUTHORS


First language

5%Fluent

speakers 4%

Non-English Speakers 91%


Evidence Based Medicine

The Evidence PyramidAb

ility t

o co

ntro

l bias

and

dem

onst

rate

caus

e and

effec

t


THAN

K%YOU

how to write a clinical article

Health & Medicine