Treatment patterns, healthcare resource utilization and costs in patients with bipolar disorder, newly treated with extended release or immediate release quetiapine fumarate using US healthcare administrative claims data

Abstract

Background: Differences in treatment patterns, health care resource use, and costs are expected among patients newly treated with quetiapine extended release (XR) or quetiapine immediate release (IR).

Objective: To compare treatment patterns, health care resource use, and costs in patients with bipolar disorder newly treated with quetiapine XR or quetiapine IR.

Methods: This was an observational, retrospective cohort study that used HealthCore Integrated Research Database-identified patients (age range, 18-64 years) with an International Classification of Disease, Ninth Revision diagnosis of bipolar disorder and ≥1 pharmacy claim for quetiapine XR or quetiapine IR between October 2, 2008, and July 31, 2010. Outcomes were as follows: patient characteristics at the index date (first claim for quetiapine XR or quetiapine IR); 12-month preindex clinical characteristics, health care resource use, and costs; and 12-month postindex treatment patterns, health care resource use, and costs, assessed using generalized linear models (adjusted for index date and preindex patient demographic characteristics, clinical characteristics, health care resource use, and costs).

Results: In total, 3049 patients with bipolar disorder were analyzed (651 in the quetiapine XR group and 2398 in the quetiapine IR group). Of patients initiating treatment with quetiapine XR, 8.8% had no change in or discontinuation of their index therapy compared with 5.7% of patients treated with quetiapine IR (adjusted odds ratio, 1.44; 95% confidence interval, 1.03-2.00; P = 0.0317). The average daily dose (adjusted mean) of quetiapine XR was higher than quetiapine IR (225 vs 175 mg/d, P < 0.0001). An average daily dose of 300 to 800 mg was reached sooner (15.6 vs 30.8 days, P = 0.0049) and in more patients (44.2% vs 27.2%, P < 0.0001) who were taking quetiapine XR compared with patients taking quetiapine IR. No differences in total health care costs were found between the cohorts; however, patients taking quetiapine XR were less likely to be hospitalized for mental health-related reasons (12.1% vs 18.3%, P = 0.0022) and incurred lower mental health-related costs (US $6686 vs US $7577, P = 0.0063) compared with patients taking quetiapine IR.

Conclusions: Treatment patterns and dosing differ in patients with bipolar disorder treated with quetiapine XR compared with those treated with quetiapine IR. Mental health-related hospitalizations and costs may be reduced in the 12 months after patients initiating treatment with quetiapine XR compared with initiating treatment with quetiapine IR.

Keywords: bipolar disorder; health care use; quetiapine IR; quetiapine XR.