Does Screening for Depressive Symptoms Help Optimize Duloxetine Use in Knee Osteoarthritis Patients With Moderate Pain? A Cost-Effectiveness Analysis

Objective Duloxetine is a treatment approved by the US Food and Drug Administration for both osteoarthritis (OA) pain and depression, though uptake of duloxetine in knee OA management varies. We examined the cost-effectiveness of adding duloxetine to knee OA care in the absence or presence of depression screening. Methods We used the Osteoarthritis Policy Model, a validated computer microsimulation of knee OA, to examine the value of duloxetine for patients with knee OA who have moderate pain by comparing 3 strategies: 1) usual care, 2) usual care plus duloxetine for patients who screen positive for depression on the Patient Health Questionnaire 9 (PHQ-9), and 3) usual care plus universal duloxetine. Outcome measures included quality-adjusted life years (QALYs), lifetime direct medical costs, and incremental cost-effectiveness ratios (ICERs), discounted at 3% annually. Model inputs, drawn from the published literature and national databases, included annual cost of duloxetine ($721-937); average pain reduction for duloxetine (17.5 points on the Western Ontario and McMaster Universities Osteoarthritis Index pain scale [0-100]), and likelihood of depression remission with duloxetine (27.4%). We considered 2 willingness-to-pay (WTP) thresholds of $50,000/QALY and $100,000/QALY. We varied parameters related to the PHQ-9 and the cost of duloxetine, efficacy, and toxicities to address uncertainty in model inputs. Results The screening strategy led to an additional 17 QALYs per 1,000 subjects and increased costs by $289/subject (ICER = $17,000/QALY). Universal duloxetine led to an additional 31 QALYs per 1,000 subjects and $1,205 per subject (ICER = $39,300/QALY). Under the majority of sensitivity analyses, universal duloxetine was cost-effective at the $100,000/QALY threshold. Conclusion The addition of duloxetine to usual care for knee OA patients with moderate pain, regardless of depressive symptoms, is cost-effective at frequently used WTP thresholds.