The association between treatment adherence and antipsychotic dose among individuals with bipolar disorder

Claims data were examined to evaluate the association between antipsychotic dose and treatment adherence among individuals with predominantly manic/mixed or depressed symptoms of bipolar disorder. Two measures of treatment adherence were used, intensity (medication possession ratio) and treatment duration (uncensored treatment episodes). Effects of higher antipsychotic doses on adherence were evaluated using multiple regression analysis. Dose effects on adherence intensity in subsequent (3-month) treatment stages were examined over 15 months. Antipsychotic treatment episodes (13 921) were analyzed. For manic/mixed individuals, risperidone, olanzapine, and typical antipsychotics showed reduced adherence intensity with higher doses in all treatment stages (P<0.05). Among depressed individuals, higher doses of olanzapine and typical antipsychotics were associated with reduced adherence intensity in all stages, with most associations reaching significance (P<0.05). Higher doses of quetiapine and risperidone were associated with increased adherence intensity in months 4-6 (P<0.05), but risperidone showed reduced intensity in months 7-9 (P<0.001). For all risperidone-treated or quetiapine-treated individuals, higher doses were associated with longer treatment durations (P<0.05). Higher doses of olanzapine and typical antipsychotics (and in manic/mixed individuals, risperidone as well) seem to adversely impact adherence intensity. Among depressed individuals, higher doses of quetiapine and risperidone are initially associated with increased adherence intensity. Int Clin Psychopharmacol 23:305-316 (C) 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins.