Review article: critical review of meta-analyses of randomized clinical trials in hepatogastroenterology.

BACKGROUND: This review attempts to identify meta-analyses performed in hepatogastroenterology, and to assess their quality and to identify simple criteria of good quality.
METHODS: Meta-analyses of randomized clinical trials in hepatogastroenterology published as full papers before 1993 were included. A quality score was defined as the sum of 27 items evaluated in each publication and coded 2 if adequate, 1 if partial and 0 if missing. Quality criteria were identified by discriminant analysis through three groups of meta-analyses defined by their quality score (poor, middle, high).
RESULTS: From 1981 to 1992, 62 publications were identified, including 42% in the last 2 years. Nineteen per cent concerned peptic ulcers, 18% oesophageal varices and 6% digestive cancers. They reported 180 meta-analyses. The quality score ranged from 14 to 40, the median was 29. Twenty-five per cent of the studies obtained a score lower than 23 and 25% a score higher than 34. Several stages of meta-analysis were poorly performed: identification and selection of trials, study of trial quality, data extraction and achievement of sensitivity analyses, subgroup and indirect analyses. Some of them led to biases and questions about the validity of results. Five criteria were significantly associated with high quality: presence of a protocol, assessment of trial quality, only randomized trials pooled, achievement of sensitivity analyses, and peer-reviewed publication.
CONCLUSIONS: In hepatogastroenterology, there is an exponential increase in publication of meta-analyses but their quality is heterogeneous. In particular, the control of the biases has to be better performed.