Economic Impact of Therapeutic Substitution of a Brand Selective Serotonin Reuptake Inhibitor with an Alternative Generic Selective Serotonin Reuptake Inhibitor in Patients with Major Depressive Disorder

BACKGROUND: To reduce pharmacy costs, managed care organizations encourage therapeutic substitution from brand to a generic product. However, little is known about whether these cost-containment strategies can also potentially lower total expenditures for payers in treatment of major depressive disorder (MDD). OBJECTIVE: To compare economic outcomes of patients with MDD who were switched from a brand selective serotonin reuptake inhibitor (SSRI) to an alternative generic SSRI for nonmedical reasons versus patients who continued on the brand SSRI. METHODS: Adult MDD patients in the Ingenix Impact Database (2003-2007) were considered "switchers" if they received treatment with a brand SSRI and were later switched to an alternative generic SSRI for nonmedical reasons. Patients who remained on the brand SSRI (nonswitchers) were matched 1:1 with switchers. All-cause, mental health-related, and MDD-related rates of hospitalizations/emergency department (ED) visits and costs over 6 months were compared both descriptively and by using adjusted regression models. A subgroup analysis on patients who were switched from escitalopram (Lexapro) to an alternative generic SSRI was also performed. RESULTS: The study included 4449 matched pairs. Compared with nonswitchers, switchers had higher risk of all-cause, mental health-related, and MDD-related use of hospitalizations/ED visits (OR 1.15, 1.34, and 1.54, respectively; all p < 0.01) and higher risk-adjusted mental health-related and MDD-related medical costs ($219 and $222, respectively; both p < 0.05). Subgroup analysis on escitalopram showed similar results; switchers experienced higher risk of any-cause, mental health-related, and MDD-related use of hospitalizations/ED visits (OR 1.21, 1.41, and 1.53, respectively; all p < 0.01) and higher risk-adjusted MDD-related medical costs ($151; p < 0.05). CONCLUSIONS: Compared with patients who continued on their patented SSRIs, patients who switched to a generic SSRI incurred more resource use of hospitalizations/ED visits and higher MDD-related health-care costs. The effects of therapeutic substitution should be carefully examined, because use of generic alternatives may not be a cost-saving strategy when total health-care costs are considered.