critical appraisal for mrcgp jim mcmorran coventry gp gp trainer editor gpnotebook ()
Post on 18-Dec-2015
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Critical Appraisal for MRCGP
Jim McMorranCoventry GPGP trainerEditor GPnotebook (www.gpnotebook.co.uk)
Analysing studies
Confounding factors.. Sample size.. Applicability of results.. Placebo controlled.. Blinded… Primary endpoints…
Critical Appraisal Methodology(from GPnotebook)1. what is the research question - for most studies there
should be a single sentence describing why the study was done and what hypothesis the authors were testing
2. the type of study design used 3. the study population investigated 4. comparator drugs and doses studied 5. sample size and power used in the study 6. primary versus secondary endpoints and subgroup
analysis 7. duration of the study 8. study follow-up 9. is there a sponsorship or publication bias
Critical Appraisal Methodology(from GPnotebook)
1. other considerations 1. intention to treat analysis 2. what p-values are used 3. what confidence intervals are used 4. comparing statistical and clinical significance of
results 5. analysis of results e.g absolute risks, relative risks,
odds ratios, hazard ratios, numbers needed to treat, numbers needed to harm, Kaplan-Meier survival curves, simple statistical test
Research question
PROACTIVE (PROspective pioglitAzone Clinical Trial In macroVascular Events) to find out whether pioglitazone
reduces cardiovascular (CV) morbidity and mortality in high-risk patients with type 2 diabetes
Type of Study Design Used Type of study: retrospective e.g. case control study prospective e.g. cohort study, randomised
controlled trial Other points regarding study design include:
was the study blinded? If so was the study blinded for the patient and the investigator (double blinded)?
was the study a crossover study? The findings from a prospective study are
more valid than those from a retrospective one
Different outcomes Different studies Coronary Heart Disease and HRT
CHD and HRT - General Practice Notebook Management of febrile child – use of tepid
sponging or not? prevention - General Practice Notebook
Study Population investigated Age of population Exclusion criteria used study population - General Practice Notebook
Study populations investigated Age when statins are effective
Statins effective for primary prevention up to the age of 70 years
WOSCOPS - General Practice Notebook Statins effective for primary prevention up to the age
of 85 years MRC / BHF Heart Protection Study - General Practice No
tebook
Is the study population comparable to those patients in primary care
Proactive study - General Practice Notebook FIELD study - General Practice Notebook
Comparitor drugs and doses studied
Is there a comparitor Drug comparator drugs in statistical studies
- General Practice Notebook
Interesting comparisons Bupropion versus varenicline for
smoking cessation varenicline - General Practice Notebook
Is the indicated length of use of medication the same for both medications
Exercise versus use of metformin in prevention of diabetes
exercise in the prevention of type 2 diabetes - General Practice Notebook
What about the dose of metformin
Sample Size and Power What is statistical power? What is the typical value of the
power of the study? Why is the power of the study
important when considering study endpoints? sample size and power of study - Gen
eral Practice Notebook
Primary Versus Secondary Endpoints The power of a study is based on the
primary endpoint of a study primary versus secondary endpoints - Gener
al Practice Notebook Headline studies where the primary
endpoint was not significant include Proactive study - General Practice Notebook FIELD study - General Practice Notebook
Duration of study
Sufficient period to allow events to occur
Long enough to relate findings to use in chronically ill patient duration of study - General Practice Noteboo
k Efficacy of topical NSAIDs versus oral NSAIDs topical non-steroidal anti-inflammatory drugs (
NSAIDs) in osteoarthritis - General Practice Notebook
Is there sponsorship or publication bias
Is the study sponsored by the pharmaceutical industry or government sponsored
is there sponsorship or publication bias - General Practice Notebook
Other considerations – a selection
Intention to treat analysis intention to treat analysis - General Practice Notebook
Comparing statistical and clinical significance statistical versus clinical significance - General
Practice Notebook NNT
number needed to treat (NNT) - General Practice Notebook
Consider how many patients are required to be treated to prevent a single stroke based on the SPARCL trial (look at CIs)
SPARCL (Stroke Prevention by Aggressive Reduction in Cholesterol Levels) trial - General Practice Notebook