Real-world data analysis of the clinical and economic burden and risk factors in patients with major depressive disorder with an inadequate response to initial antidepressants

Abstract

Aim: We aimed to determine the incidence of and identify the factors associated with treatment-resistant depression (TRD), psychiatric conditions, hospitalization, and cost in patients with major depressive disorder (MDD) who were treated using second-line strategies after an inadequate response to initial antidepressants (AD). Materials and methods: Using South Korean National Health Insurance claims data (1 January 2013 to 30 June 2018), we conducted a retrospective cohort analysis in newly treated patients with MDD who subsequently switched or added AD, or added atypical antipsychotics (AAPs) as a second-line treatment. We assessed the incidence of treatment-resistant depression (TRD), psychiatric conditions, and hospitalization for the first 2 years and costs in the third year. Odds ratios (ORs) or relative ratios were estimated using logistic and linear regression models to identify the risk factors for clinical and economic outcomes. Results: In 15,887 patients, the TRD was 16.81% during the 24-month follow-up period (14.14% in switching AD, 19.65% in adding AD, and 19.91% in adding AAP; p < 0.0001). When adding AD or AAP, the OR of TRD was 1.43 (95% confidence interval (CI): 1.30–1.56) and 1.42 (95% CI: 1.23–1.65), respectively, compared to switching AD. However, these factors were not associated with the incidence of psychiatric conditions. Adding AAP increased hospitalization (OR = 1.25, 95% CI: 1.11–1.41), the number of inpatient days by 2.57-fold (95% CI: 1.75–3.76), and cost by 1.20-fold (95% CI: 1.02–1.40), compared to switching AD; adding AD did not show a significant association with these outcomes. Conclusions: In patients with MDD with inadequate responses to initial AD, TRD still occurred after subsequent treatments according to clinical guidelines. Since the effectiveness of second treatment strategies can differ in reality, further analysis of the clinical and economic evidence regarding second treatment strategies, such as adding AD or AAP, is needed using real-world data.