The cost of antidepressant drug therapy failure: a study of antidepressant use patterns in a Medicaid population.

Paid claims data from the California Medicaid (Medi-Cal) program were used to examine the utilization of antidepressants and to estimate the costs of antidepressant treatment failure for patients with major depressive disorders (MDD). Data for 6713 new patient episodes of antidepressant therapy were available for the analysis; over 45% of these patients never achieved a minimum daily dose of antidepressants indicative of treatment for depression and were excluded from further analysis. That left a possible depression patient population of 3664 patients of which 2344 patients had a minimum of 1 full year of post-episode data for analysis. Only 81 patients (3.5%) displayed antidepressant use patterns consistent with the successful treatment of MDD; 296 patients (12.6%) displayed use patterns suggestive of antidepressant treatment failure. The remaining 1967 (84%) patients could not be clearly classified; they were either (1) patients being treated for problems other than MDD, (2) MDD patients who were being prescribed subtherapeutic doses by their physician due to side effects or other reasons, (3) MDD patients who were noncompliant for a variety of reasons, or (4) MDD patients who had prematurely terminated antidepressant therapy. Multivariate regression analysis was used to estimate the costs associated with MDD treatment failure. These analyses indicated that MDD treatment failure resulted in increased costs of approximately $1043 in the first post-episode year (p less than .10). These increased costs were primarily due to higher hospital costs ($921, p less than .05), while drug costs were reduced by $222 (p less than .001).