Combination quetiapine therapy in the long-term treatment of patients with bipolar I disorder

OBJECTIVE Determine the long-term effectiveness of quetiapine in combination with standard treatments in preventing relapses for patients with bipolar I disorders. METHOD Twenty-one outpatients with type I bipolar disorder who had inadequate responses to ongoing standard therapies were treated with add-on quetiapine in an open-label study. The quetiapine dose was increased until clinical response occurred. Illness response was assessed using the Clinical Global Impression (CGI) scale. Relapse rates before and during quetiapine treatment were compared by calculating incidence risk ratios. RESULTS Quetiapine was added to ongoing standard therapy for 26 to 78 weeks. Thirteen patients received combination therapy for at least 52 weeks. The mean quetiapine dose received was 518 +/- 244 mg/day. There were highly significant improvements in overall relapse rate, manic/mixed relapse rate, and depression relapse rate in the period during quetiapine treatment compared with the period before quetiapine was initiated. The calculated relative risk of relapse in the absence of quetiapine treatment was 2.9 overall (95% confidence interval, 1.5 approximately 5.6), 3.3 for manic/mixed relapse (95% confidence interval, 1.5 approximately 7.1), and 2.4 for depressive relapse (95% confidence interval, 1.3 approximately 4.4). The mean Clinical Global Impression scores improved significantly from baseline during 26 weeks of quetiapine treatment in 21 patients (p = 0.002) and remained significantly better during a 52-week treatment period in 13 patients (p = 0.036). CONCLUSION Long-term treatment with quetiapine combination therapy reduced the probability of manic/mixed and depressive relapses and improved symptoms in patients with bipolar I disorder who had inadequate responses to ongoing standard treatment.