Criteria for evaluating improvement in schizophrenia in psychopharmacological research (with special reference to gamma endorphin fragments).

A review of treatment trials with DT gamma E revealed widely discrepant results. Relevant variables were the variety of measures employed for monitoring psychotic symptoms, and the different criteria used to judge the degree of improvement. The authors suggest a uniform outcome criterion for early trials of new treatments, which would generate more consistent and comparable results between studies, and give a stronger indication of the value of the treatment under test. When the data from the various treatment trials of DT gamma E were reanalysed, applying a uniform outcome criterion of improvement of a change of 80% or more on rating-scale score, the results were more consistent than would have been suspected from the original reports.