Meta-Analyses of Randomized Control Trials

Abstract

Meta-analysis attempts to analyze and combine the results of previous reports. We have updated our 1987 survey of 86 meta-analyses of randomized control trials in the English-language literature with an additional 78 reports. We have evaluated the quality of these meta-analyses using a scoring method we have devised that lists 23 items in six major areas — study design, combinabiliry, control of bias, statistical analysis, sensitivity analysis, and application of results. Of the 23 individual items, the mean number satisfactorily addressed was 7.63 ± 2.84 (mean ± S.D.) for 40 papers published from 1955 to 1982,6.80 ± 3.86 for 66 papers published from 1983 to 1986, and 11.91 ±4.79 for 58 papers published from 1987 to 1990 (F= 31.3, P<0.001). We conclude that there has been a noticeable improvement over this short time, but there still exists an urgent need for improved methodology in searching the literature, evaluating the quality of trials, and synthesizing the results.