Objective: Treatment-resistant depression (TRD) imposes substantial cost from the perspective of employers. The objective of this study was to assess direct healthcare costs and indirect (disability and medical-related absenteeism) costs associated with TRD compared with non-treatment-resistant major depressive disorder (MDD).
Methods: Employees with one or more inpatient, or two or more outpatient/other MDD diagnoses (ICD-9-CM: 296.2x, 296.3x) from 2004 through 2007, ages 18-63 years, were selected from a claims database. Employees who initiated a third antidepressant following two antidepressant treatments of adequate dose and duration or who met published TRD criteria were classified as TRD likely (N = 2312). The index date was the date of the first antidepressant, starting 1/1/2004. The control group was an age- and sex-matched cohort of employees with MDD but without TRD. All had continuous eligibility during the 6-month pre-index (baseline) and 24-month post-index (study) period. McNemar tests were used to compare baseline comorbidities. Wilcoxon signed-rank tests were used to compare costs from employer perspective.
Results: TRD-likely employees were on average 48 years old, and 64.8% were women. Compared with MDD controls, TRD-likely employees had significantly higher rates of mental-health disorders, chronic pain, fibromyalgia, and higher Charlson Comorbidity Index. Average direct 2-year costs were significantly higher for TRD-likely employees ($22,784) compared with MDD controls ($11,733), p < 0.0001. Average indirect costs were also higher among TRD-likely employees ($12,765) compared with MDD controls ($6885), p < 0.0001.
Limitations: Limitations of claims data related to accuracy of diagnosis coding and lack of clinical information apply to this study.
Conclusions: Based on comorbidities and healthcare resources used, patients with TRD appeared to represent a clinically complex subgroup of individuals with MDD. TRD was associated with significant cost burden.