OBJECTIVES: To evaluate and compare healthcare resource utilization (HCRU) and costs between major depressive disorder (MDD) patients diagnosed with and without comorbid substance abuse (SA).

METHODS: Using the Truven Health Analytics MarketScan® Medicaid, Commercial, and Medicare Supplemental databases (7/1/15-6/30/16-Medicaid, 7/1/15-3/31/16-Commercial and Medicare Supplemental), adult patients with MDD were identified if they initiated an oral atypical antipsychotic augmentation therapy with their antidepressant and had ≥6 months continuous enrollment before (baseline) and after (follow-up) the first day of treatment (index date). Presence of comorbid SA was determined based upon having ≥1 claim with a relevant ICD-9/10 or procedure code during the baseline. Multivariable regression models were conducted to estimate adjusted utilization and costs, controlling for demographic and clinical characteristics, insurance type, baseline medication, and baseline hospitalization.

RESULTS: Of 4,862 patients with MDD who initiated atypical antipsychotic augmentation therapy, 853 (17.5%) had comorbid SA; the remaining 4,009 (82.5%) were without SA. At baseline, patients with SA were younger [mean (SD) 42.3 (14.3) years vs. 48.5 (16.3) years], and had a higher hospitalization rate (55.6% vs. 19.2%) (p<0.001) than those without SA. Controlling for baseline differences, patients with SA had statistically significantly higher adjusted all-cause and psychiatric hospitalization rates [17.0% vs. 11.8% (all-cause); 9.8% vs. 4.4% (psychiatric)] and medical costs [$16,912 vs. $10,798 (all-cause); $8,854 vs. $2,832 (psychiatric)] during the follow-up period (p<0.001).

CONCLUSIONS: MDD patients with comorbid SA had higher all-cause and psychiatric specific hospitalization rates and costs. Efforts to address comorbid SA in MDD patients may help reduce healthcare utilization and costs.