OBJECTIVES : Major depressive disorder (MDD) is a progressive disease. Patients experience decreased remission rates with each additional failed therapy and longer depressive episodes are associated with poorer outcomes and increased rates of relapse. This analysis evaluated the total cost of care of patients diagnosed and treated for MDD stratified by the number of treatment steps needed to meet episode resolution as proxied by treatment stability.

METHODS : In a retrospective cohort study, we used Truven Health Analytics MarketScan® databases from 2015 to 2016. Adults diagnosed with MDD starting on an antidepressant were followed for 12 months. Outcomes were compared between patients who achieved treatment stability (proxy for episode resolution) on 1^st step of therapy, 2^nd step of therapy, 3+ steps of therapy and/or did not achieve treatment stability, and in patients who had patterns of non-adherence to treatment. Treatment stability was defined as remaining on treatment for a minimum of 4-9 months after an acute phase of treatment per clinical guidelines. Medical costs were reported by insurance type.

RESULTS : A total of 94,938 patients met selection criteria. The average number of medical visits increased with the number of treatments (21.4, 22.5, 30.4, 26.4 for patients stabilizing at 1, 2, and 3+ steps of therapy and non-adherent patients respectively). Unadjusted average total cost of care in the first 12 months in the subset of commercially insured patients was $9,408, $10,733, $18,805 and $11,899 in patients stabilizing after 1 step, 2 steps, receiving 3 or more treatments, and non-adherent patients respectively. Differences in total costs of care were attributable to the treatment of both MDD and co-morbid conditions.

CONCLUSIONS : Yearly total cost of care is positively correlated with the number of antidepressants a patient receives before finding therapeutic stability. Early achievement of episode resolution (treatment stability) may avert increases in the total cost of care.