Methodological quality of economic modelling studies. A case study with hepatitis B vaccines.

The notable increase in the quantity of economic evaluations in the last 2 decades has not been matched by good methodological standards. This problem is particularly evident in the field of economic evaluations of hepatitis B vaccines. The results of 2 systematic reviews conducted by us in 1993 and 1996 showed three problem areas. A sizeable minority of study reports failed to provide a clear study aim, showing a basic ignorance of the first rule of conducting scientific research. The basic epidemiological assumptions upon which the economic models were based showed variability which persisted even after stratification, raising the question of the accuracy of the epidemiological knowledge base of hepatitis B infection and its progression. Lastly, many of the studies showed weaknesses in basic methods of conducting and reporting economic evaluations. Examination of these problem areas led us to conclude that no conclusions about the efficiency of hepatitis B vaccines could be drawn from the available evidence. Addressing the problem of poor methodological standards concerns the whole research community. However, as a proportion of economic evaluations are published, one obvious means of exerting pressure to increase and maintain methodological standards is the editorial and peer review process. Editors of specialist and general medical journals should agree on and enforce common explicit guidelines for study conduct and reporting, following the example of the British Medical Journal.