The growth of health-related meta-analyses published from 1980 to 2000.

A MEDLINE search was conducted to estimate trends in the growth of health-related meta-analyses published during the past two decades. Employing a more specific than sensitive search strategy, and not supplementing these results with known sources of published meta-analyses or manual search strategies, 3,025 probable meta-analyses were selected from the 5,128 citations identified. The data showed a definitive upward (and generally linear) trend across time with no evidence for this genre of research either leveling off or decreasing.