Duloxetine is an FDA-approved treatment for both osteoarthritis (OA) pain and depression, but uptake of duloxetine in knee OA management varies. We examined the cost-effectiveness of adding duloxetine to knee OA care with or without depression screening.
We used the Osteoarthritis Policy Model, a validated computer microsimulation of knee OA, to examine the value of duloxetine for knee OA patients with moderate pain by comparing three strategies: 1) usual care (UC); 2) duloxetine for those who screen positive for depression on the Patient Health Questionnaire 9 (PHQ-9) + UC; and 3) universal duloxetine + UC. Outcomes included quality-adjusted life years (QALYs), lifetime direct medical costs, and incremental cost-effectiveness ratios (ICERs), discounted at 3% annually. Model inputs, drawn from published literature and national databases, included: annual cost of duloxetine, $721-$937; average pain reduction for duloxetine, 17.5 points on the WOMAC pain scale (0-100); likelihood of depression remission with duloxetine, 27.4%. We considered two willingness-to-pay (WTP) thresholds of $50,000/QALY and $100,000/QALY. We varied parameters related to the PHQ-9 and duloxetine's cost, efficacy, and toxicities to address uncertainty in model inputs.
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/subject (ICER=$39,300/QALY). Under the majority of sensitivity analyses, universal duloxetine was cost-effective at the $100,000/QALY threshold.
Adding duloxetine to usual care for knee OA patients with moderate pain, regardless of depressive symptoms, is cost-effective at frequently-used WTP thresholds.