Olanzapine plasma level in relation to antimanic effect in the acute therapy of manic states

The aim of this study was to evaluate internal as well as external validity of the two most frequently used mania scales, the Young Mania Rating Scale (YMRS) and the Bech-Rafaelsen Mania Scale (MAS), in patients with DSM-IV mania. Mokken analysis was used to evaluate internal validity in which a coefficient of homogeneity of 0.40 or higher indicates that the total score is a sufficient statistic. The external validity was evaluated by plasma-level relationship of olanzapine. In total, 20 patients with DSM-IV mania were analysed, and the coefficient of homogeneity was acceptable for the MAS, but not for the YMRS. In a subgroup of females who over 2 weeks had received a fixed dose of 20 mg olanzapine daily, a significant association was found between MAS scores and plasma levels, but this association was not obtained with the YMRS. In conclusion, the MAS was found superior to the YMRS in regard to both internal and external validity.