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

Abstract

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). 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. 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. 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). 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.