Misleading meta-analysis

doi:10.1136/bmj.311.7007.753c

From trainee to consultant, BMJ Group offers doctors around the world tailored information, special events, learning resources and recruitment services at every step along their career path.

... by doctors, for doctors, for patients
We are open for entries!

Online learning

BMJ Learning

High-quality CME / CPD for doctors and other healthcare professionals. BMJ Learning features hundreds of accredited, peer-reviewed learning modules in text, video, and audio formats. Find out more

Courses and Qualifications

BMJ Masterclasses

BMJ Masterclasses, led by experts, help clinicians to use the latest evidence and recent guidelines in practice and meet their CPD/CME requirements. Find out more

Exam Preparation

The leading provider of online exam preparation, helping over 167,000 healthcare professionals to pass their exams. Find out more

onExamination

Search all BMJ comment articles:

From

Limit by

Access to the full text of this article requires a subscription or payment. Please log in or subscribe below.

Matthias Egger, Senior research fellow,
George Davey Smith, Professor of clinical epidemiology

Department of Social and Preventive Medicine, University of Berne, CH-3012 Berne, Switzerland
Department of Social Medicine, University of Bristol, Bristol BS8 2PA

EDITOR,--In their response1 to our editorial on misleading meta-analysis2 A Perry and R Persaud state that we ignored the degree of heterogeneity among different studies. We examined the case of intravenous magnesium in acute myocardial infarction, a treatment recently shown to be of no benefit in a trial.3 We argued that the asymmetrical funnel plot (a plot of the estimates of effect sizes against the sample size) should have alerted meta-analysts to the possible presence of bias. The erroneous conclusion …