Estimating the Impact of Delayed Treatment for Major Depressive Disorder Using a Continuous-Time Patient-Level Simulation Model

BACKGROUND: Real-world evidence indicates that most patients treated for major depressive disorder (MDD) typically cycle through different selective serotonin reuptake inhibitors (SSRIs) following initial diagnoses, but many remain untreated.

OBJECTIVES: To examine clinical and economic outcomes, costs, and cost-effectiveness of a treatment pathway comprised of SSRI monotherapies through four lines of therapy vs. no treatment, for adults (aged 18-64) newly diagnosed with MDD in the United States.

METHODS: The open-source IVI-MDD Value Model simulates patients to estimate clinical and economic outcomes for different treatment pathways, and includes three health states: non-response, partial response, and complete response (CR). Two treatment pathways were modeled over a 5-year time horizon: no active treatment vs. four lines of treatment with differing SSRI monotherapy in each. Clinical outcomes include % achieving remission, time to CR, duration of remission, and quality-adjusted life years (QALY) gained. Cost outcomes include healthcare costs, productivity loss, and total societal costs. Costs and QALYs were discounted at 3% annually.

RESULTS: Compared with untreated individuals, treated individuals were more likely to achieve remission (78.5% vs. 34.0%), achieved first CR more quickly (7.1 vs. 24.9 months), and spent more time in remission (21.0 vs. 2.4 months), resulting in higher QALYs over 5 years (2.78 vs. 1.93). Average healthcare costs were lower for SSRI-treated individuals ($48,909 vs. $64,068), as was productivity loss ($53,561 vs. $69,927). Average total healthcare, productivity, and transportation costs over 5 years were an estimated $103,803 for SSRI-treated vs. $133,995 for untreated individuals. Estimated cost per month in remission was $4,938 for SSRI treatments and $56,344 for untreated. Net monetary benefit, calculated as $150,000 per QALY times QALYs gained minus costs, was estimated as $312,892 for SSRI treatment vs. $157,776 for no active treatment.

CONCLUSIONS: Treating patients with SSRIs is estimated to be cost-saving relative to no treatment.