Introduction: Early antidepressant discontinuation has been linked to significant clinical and economic consequences. Clinical practice guidelines suggest that treatment should last for at least 3 to 9 months into the continuation phase; however, 30% of patients discontinue therapy within 30 days, and over 40% discontinue therapy within 90 days of initiation, primarily due to adverse events. Clinical trials have shown that controlled-release (CR) paroxetine has a favorable tolerability profile when compared to immediate-release (IR) paroxetine, which may result in lower discontinuation rates and improved economic outcomes. This is the first study to directly compare treatment discontinuation rates and health care expenditures of a CR selective serotonin reuptake inhibitors with its IR counterpart.
Methods: This matched retrospective study used claims from a national managed care database to assess differences in discontinuation rates and health care expenditures between paroxetine CR and IR for treating depression and/or anxiety. Discontinuation was assessed by survival analysis, and health care expenditure was assessed using average monthly medical and pharmacy charges.
Results: There were 1275 paroxetine CR patients and 2550 paroxetine IR patients matched in the analysis. At 90 days, 62% of paroxetine CR patients continued therapy versus 56% of paroxetine IR patients. At 180 days, 51% of paroxetine CR patients continued therapy versus 42% of paroxetine IR patients. When evaluating all medical charges, paroxetine CR patients incurred US$119 less per month than paroxetine IR patients (P = 0.054).
Conclusions: Patients receiving paroxetine CR remained on therapy longer than patients on paroxetine IR, which resulted in lower total monthly medical costs for patients receiving paroxetine CR. Differences in costs were primarily driven by reduction in hospitalization expenditures.