We were disappointed that Sudre et al 1 felt there was insufficient documentation and excessive variability in studies of education programmes for adults with asthma published between 1979 and 1998. We feel that their conclusion is largely because they did not perform a rigorous systematic review of papers in this area.

Systematic reviews of research evidence are undoubtedly invaluable scientific activities. They establish whether scientific findings are consistent and can be generalised across populations, settings, and other variations. Systematic reviews should be based on the “gold standard” of published randomised clinical trials. However, in the 77 trials reported Sudre et al included 35 studies which were not randomised controlled trials. They also give no information about which interventions were found to have statistically significant effects. They include a study which simply asked patients whether they preferred audiovisual information or written information and did not have any intervention,2 a study which has not been published,3 …