SUMMING-UP EVIDENCE - ONE ANSWER IS NOT ALWAYS ENOUGH

Are meta-analyses the brave new world, or are the critics of such comb ined analyses right to say that the biases inherent in clinical trials make them uncombinable? Negative trials are often unreported, and hen ce can be missed by meta-analysts. And how much heterogeneity between trials is acceptable? A recent major criticism is that large randomise d trials do not always agree with a prior meta-analysis. Neither indiv idual trials nor meta-analyses, reporting as they do on population eff ects, tell how to treat the individual patient. Here we take a more ro unded approach to meta-analyses, arguing that their strengths outweigh their weaknesses, although the latter must not be brushed aside.