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Critical Appraisal for Therapy Articles

THERAPY STUDY:Are the results of the trial valid? (Internal Validity

!hat "uestion did the study as#?Patients –Intervention -

Comparison -Outcome(s) –

$a% R& !as the assi'nent of )atients to treatents randoised?What is best? Where o I fin the information?

Centralised computer randomisation is iealan often use in multi-centre trials! "mallertrials may use an independent  person (e!#$ thehospital pharmacy) to %police& theranomi'ation!

The Methodsshoul tell you ho patients ereallocate to #roups an hether or notranomisation as conceale!

This paper *es  +o  ,nclear

Comment

$*% R& !ere the 'rou)s siilar at the start of the trial?What is best? Where o I fin the information?

If the ranomisation process ore (that is$

achieve comparable #roups) the #roups

shoul be similar! The more similar the #roups

the better it is!

There shoul be some inication of hetherifferences beteen #roups are statisticallysi#nificant (ie! p values)!

The Results shoul have a table of ./aselineCharacteristics. comparin# the ranomi'e#roups on a number of variables that coulaffect the outcome (ie! a#e$ ris factors etc)! Ifnot$ there may be a escription of #roupsimilarity in the first para#raphs of the Results section!

This paper *es  +o  ,nclear

Comment

+a% A , Aside fro the allo-ated treatent. /ere 'rou)s treated e"ually?What is best? Where o I fin the information?

 Apart from the intervention the patients in theifferent #roups shoul be treate the same$e#!$ aitional treatments or tests!

0oo in the Methods section for the follo-upscheule$ an permitte aitional treatments$etc an in Results for actual use!

This paper *es  +o  ,nclear

Comment

+*% A , !ere all )atients /ho entered the trial a--ounted for? , and /ere theyanalysed in the 'rou)s to /hi-h they /ere randoised?

What is best? Where o I fin the information?

0osses to follo-up shoul be minimal –preferably less than 123! 4oever$ if fepatients have the outcome of interest$ then

even small losses to follo-up can bias theresults! Patients shoul also be analyse in the#roups to hich they ere ranomise –5intention-to-treat analysis’ !

The Results section shoul say ho manypatients ere 6anomise (e#!$ /aselineCharacteristics table) an ho many patients

ere actually inclue in the analysis! *ou illnee to rea the results section to clarify thenumber an reason for losses to follo-up!

This paper *es  +o  ,nclear

Comment

0% 1 & !ere easures o*2e-tive or /ere the )atients and -lini-ians #e)t 3*lind4to /hi-h treatent /as *ein' re-eived?

What is best? Where o I fin the information?

It is ieal if the stuy is 5ouble-bline7 – thatis$ both patients an investi#ators are unaareof treatment allocation! If the outcome is

objective (e#!$ eath) then blinin# is lesscritical! If the outcome is subjective (e#!$symptoms or function) then blinin# of the

8irst$ loo in the Methods section to see if thereis some mention of masin# of treatments$ e#!$placebos ith the same appearance or sham

therapy! "econ$ theMethods

 section shoulescribe ho the outcome as assesse anhether the assessor9s ere aare of the

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Critical Appraisal for Therapy Articles

outcome assessor is critical! patients: treatment!

This paper *es  +o  ,nclear

Comment

!hat /ere the results?

$% Ho/ lar'e /as the treatent effe-t?;ost often results are presente as ichotomous outcomes (yes or not outcomes that happen oron:t happen) an can inclue such outcomes as cancer recurrence$ myocarial infarction aneath! Consier a stuy in hich

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Critical Appraisal for Therapy Articles

+% Ho/ )re-ise /as the estiate of the treatent effe-t?The true ris of the outcome in the population is not non an the best e can o is estimate thetrue ris base on the sample of patients in the trial! This estimate is calle the )oint estiate!We can #au#e ho close this estimate is to the true value by looin# at the confience intervals

(CI) for each estimate! If the confience interval is fairly narro then e can be confient that ourpoint estimate is a precise reflection of the population value! The confience interval also proviesus ith information about the statistical si#nificance of the result! If the value corresponin# to noeffe-t falls outsie the F=3 confience interval then the result is statistically si#nificant at the 2!2=level! If the confience interval inclues the value corresponin# to no effe-t then the results arenot statistically si#nificant!

!ill the results hel) e in -arin' for y )atient? (E7ternalValidity8A))li-a*ility

The Guestions that you shoul as before you ecie to apply the results of the stuy to yourpatient are

• Is my patient so ifferent to those in the stuy that the results cannot apply?

• Is the treatment feasible in my settin#?

•

Will the potential benefits of treatment outei#h the potential harms of treatment for mypatient?

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