Schizophrenia: do we really need placebo-controlled studies?

To investigate whether placebo control is necessary to prove efficacy in short-term studies in schizophrenia.

This study compares the efficacy results of placebo-controlled studies versus positive controlled studies, that is controlled studies without a placebo control, in the short-term treatment of chronic schizophrenia.

Concerning mean improvement on the BPRS, the placebo arms showed in two cases a worsening, in one case almost no change, and in the remaining studies (6) the improvement was between 1 and 5%. The percentage mean improvement in the haloperidol arms of the placebo-controlled studies was comparable to the percentage mean improvement in the corresponding arms of the non-placebo-controlled studies. The highest percentage responders in the placebo-groups was 43% and the lowest was 6%. Moreover the responder rates in the atypical antipsychotic and haloperidol arms of the non-placebo-controlled studies were, in two of the three studies, in the same order of magnitude as the responder rates of the placebo arms in the placebo-controlled studies. The overall dropout rates in the placebo arms was between 48% and 80% and were higher than the drop out rates in the atypical neuroleptic arms and haloperidol arms of the placebo-controlled studies. The dropout rates due to an insufficient response in the atypical neuroleptic arms and haloperidol arms of the non-placebo-controlled studies were lower when compared to corresponding treatment arms of the placebo-controlled studies.

In contrast to the mean improvement on the BPRS, responder rates in the placebo arms varied considerably from study to study. Responder rates in the atypical antipsychotic and haloperidol arms of the non-placebo-controlled studies were, in two of the three studies, of the same order of magnitude as the responder rates of the placebo arms in the placebo-controlled studies. These results indicate that placebo control is necessary. Moreover as responders are a more clinically relevant outcome measure when compared to mean improvement on a rating scale, placebo-controlled studies are still needed. However, consensus on responder definition should be agreed upon. For the moment, alternatives to placebo-controlled studies are inadequate in demonstrating efficacy in studies with schizophrenic patients.