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Letter: Meta-analysis can be statistically misleading

¹ West Middlesex University Hospital London London, UK
² All India Institute of Medical Science Delhi, India

The first 150 words of the full text of this article appear below.

The double blind randomised controlled trial (RCT) is the basis of good evidence-based medicine because it eliminates problems of bias and confounding. However, systematic reviews show different RCTs arriving at diametrically opposite conclusions. The reason for this is that the samples for the RCTs are drawn from different populations and it reflects the truth in those various populations. This matter is often overlooked when meta-analysis is done. When RCTs are aggregated in a meta-analysis, we have to aggregate the populations they represent—not the sample sizes. Large samples from small populations will get undue weightage otherwise. Meta-analysis as done presently can be misleading and unreliable.

In response: ... but they also present an opportunity to learn more.

When RCTs are consistent across a variety of populations and settings, we should feel more secure about the applicability of the intervention. If it works in low risk and high risk, young and old, east and west, it will probably work in my patient. However, as . . . [Full text of this article]