Cost of treating bipolar disorder in the California Medicaid (Medi-Cal) program

Background: Bipolar disorder affects approximately 1% of the population at an annual cost of $45 billion in the US. Estimates of non-compliance with mood stabilizer therapy range as high as 64%. The objective of this study was to document the use patterns with mood stabilizers achieved by patients with bipolar disorder and to estimate the direct health care costs associated with sub-optimal drug therapy. Methods: Paid claims for 3349 California Medicaid patients with bipolar disorder were used to document the use patterns for mood stabilizers achieved by patients with bipolar disorder. The impact of the patient’s drug use patterns on likelihood of antipsychotic or antidepressant use within 1 year and health care costs incurred during the first posttreatment year were also estimated. Results: Only 42.4% of patients used a mood stabilizer during the first posttreatment year; over 60% of treated patients switch or augment their initial therapy within 1 year, and only 5.5% of patients used a mood stabilizer consistently for 1 year. Direct health care costs were significantly higher among those patients who delayed or did not use mood-stabilizing agents during the first year. Limitations: Medi-Cal covers poor and disabled patients and is not representative of the general population. Paid claims data do not include clinical markers for severity of illness or treatment response. Conclusions: Suboptimal use patterns for mood stabilizing medications were frequent and costly. Strategies to improve compliance with mood stabilizer regimens, along with new treatment options, are needed to improve treatment outcomes.