BMC Medical Research Methodology | Full text | Characteristics of meta-analyses and their component studies in the Cochrane Database of Systematic Reviews: a cross-sectional, descriptive analysis

Background

Cochrane systematic reviews collate and summarise studies of the effects of healthcare interventions. The characteristics of these reviews and the meta-analyses and individual studies they contain provide insights into the nature of healthcare research and important context for the development of relevant statistical and other methods.

"Some of the more widely studied medical specialty areas in the CDSR include meta-analyses that are able to draw upon a wealth of studies, the largest containing 294 [15], whilst 1% of meta-analyses contain 28 studies or more. Among the 11 specialty categories we used, cancer had a slightly higher median number of included studies (5) than any of the other categories."

"Study sizes show notable variation across medical specialties. The medians and quartiles are highest in cancer, and high also for meta-analyses in the areas of infectious diseases and gynaecology, pregnancy and birth. Study sizes tend to be lower in the areas of mental health and behavioural conditions and pathological conditions, symptoms and signs."