Critical Reading VTS 22/04/09

“How to Read a Paper”. Series of articles by Trisha Greenhalgh - published in the BMJ - also available as a book from BMJ Publications. How to Read a Paper: The Basics of Evidence Based Medicine. 2nd ed. London: BMJ, 2001.

Home page: BMJ archive

Main Points Many papers published in medical journals have potentially serious methodological flaws When deciding whether a paper is valid and relevant to your practice, first establish what specific clinical question it addressed Questions to do with drug treatment or other medical interventions should be addressed by double blind, randomised controlled trials Questions about prognosis require longitudinal cohort studies, and those about causation require either cohort or case-control studies Case reports, though methodologically weak, can be produced rapidly and have a place in alerting practitioners to adverse drug reactions

The Christopher Centre, University of Valparaiso The Medline Database Getting your Bearings (Deciding What the Paper Is About) Assessing the Methodological Quality of Published Papers

Statistics for the Non-statistician I: Different Types of Data Need Different Tests Statistics for the Non-statistician II: "Significant" Relations and Their Pitfalls Papers that Report Drug Trials Papers that Report Diagnostic or Screening Tests Papers that Tell You What Things Cost (Economic Analyses) Papers that Summarize Other Papers (Systematic Reviews and Meta-Analyses) Papers that Go Beyond Numbers (Qualitative Research)

University of Sheffield Core Library for Evidence Based Practice

BBC - Things to Consider when Reading Medical Research Where does the new research first appear? If something is in a peer-reviewed journal it is more likely to be believed than if it is written up in a non-peer-reviewed journal. To make a decision about a paper, start off by being very cynical and see if it convinces you. Publication in the BMJ does not guarantee that it has been well-researched. Is the experiment well-designed? If the purpose of the study is to decide whether a particular drug is the best treatment for a disease, the ideal design is a double blind randomised controlled trial, where neither the patients nor the researchers know who is on the active drug. Problems with double blind controlled trials If a paper claims to have used a double blind controlled trial, ask if it is really blind. Check that they are measuring the right thing. If you are going to use the results of the study to change things, e.g. changing treatment, you need to be certain that a treatment is of benefit. If several different researchers in the past have done several different studies, they could be analysed together as a meta analysis.

Matched and Unmatched Make sure that the control is as similar as possible to the group who are receiving the treatment. One way of doing this is to match each person in the treatment group with someone in the control group of similar sex, age and occupation. If this is possible, better results are usually obtained. Case Control Studies The important thing to consider when reading one of these papers is ‘Are the controls as similar as possible?' or are they just the ones it was convenient to access? How was the research funded? E.g. drug company research may be more questionable than independent research.

Reading a paper - READER  Relevant?  Educational? Does it add anything?  Applicable? Primary-care based?  Discrimination - does it answer the questions it set out to? Any patients excluded? Appropriate design / statistics? Concepts understood – risk, NNT, etc?  Evaluation (oveRall) “RCT of the READER method of critical appraisal in general practice” MacAuley et al, BMJ, 1997, 316, 134 (11 th April)