GENERALIZABILITY OF RESULTS FROM RANDOMIZED DRUG TRIALS - A TRIAL ON ANTIMANIC TREATMENT

Background Exemplified by a randomised trial on antimanic treatment, t his paper addresses the question of whether selection of patients for drug trials may limit the applicability of study results from the rand omised patients to a wider population. Method During a two-year period , all consecutively admitted patients from a defined catchment area we re screened for inclusion criteria concerning age, diagnosis and sever ity of illness. The subsequently excluded subgroups of patients were c ompared with the randomised patients by multivariate data analysis. Re sults One hundred and sixty-Four patients met the inclusion criteria. However, after exclusion for various reasons, only 27 (17%) patients r emained for randomisation. The randomised patients and the excluded pa tients differed substantially Conclusions The generalisability of tria l results is limited. Reports of randomised drug trials should careful ly describe the screening procedure for inclusion and, when possible, present relevant comparisons between the randomised patients and the v arious subgroups of excluded patients.