The development of study exit criteria for evaluating antimanic compounds

There is increasing interest on the part of investigators and the public at large in finding ways to study and improve treatments for the seriously mentally ill without exposing such individuals to unnecessary risks. One group of particular interest in this regard are patients suffering from acute mania. We set out to define "exit" criteria or novel clinical endpoints that might help to assess the efficacy of antimanic compounds. We sought a method that would be safer, more economical, and less sensitive to nonspecific factors in the clinical environment while still allowing unambiguous assessment of efficacy.

From a pool of subjects being screened for or already participating in intervention studies, we retrospectively identified 76 admissions of patients with a manic or mixed episode according to DSM-IV. We fit a mixed-effects regression model to all available data obtained using the Bech-Rafaelsen Mania Scale from admission to day 28 of treatment. Using the estimated model coefficients, we obtained empirical Bayes (EB) estimates of each subject's trend coefficients based on (1) all available data and (2) data through day 11 of treatment for mania.

We found a high correlation (r = .67) between EB estimates of final response at day 28 and actual day 28 scores on the Bech-Rafaelsen scale based on scores through day 11. When subjects were categorized as full, partial, or nonresponders according to their final Bech-Rafaelsen score, we were able to show that only 2 of the 23 predicted nonresponders became full responders, 27 of the 31 predicted full responders became full responders, and 16 of the 22 predicted partial responders became partial or full responders.

We conclude on the basis of this chart review study that it should be possible to define exit criteria for trials assessing the efficacy of antimanic compounds on the basis of relatively short duration exposure to experimental treatment.