A single-blind placebo run-in study of venlafaxine XR for activity-limiting osteoarthritis pain

Abstract

Objective: Osteoarthritis pain is a significant problem for our aging population. Non-steroidal anti-inflammatory drugs and opioids are effective treatments, but have significant adverse effects, so there is a need for alternative treatments. Selective norepinephrine-serotonin reuptake inhibitor antidepressants may provide a new treatment option for osteoarthritis pain.

Methods: We performed a single-blind placebo run-in trial of 150-225 mg of venlafaxine in 18 subjects with activity-limiting osteoarthritis pain. Each subject received 2 weeks of placebo followed by 10 weeks of venlafaxine. The primary outcome was reduction in average pain intensity between 2 and 12 weeks. For subjects not completing the trial, their last observation was carried forward as an imputed outcome.

Results: Average pain on the Brief Pain Inventory (BPI) was 4.7 at baseline, 4.4 after the 2-week placebo run-in, and 3.3 at 12 weeks (25% decrease, P = 0.03). Nine subjects (50%) reported at least 30% pain reduction between weeks 2 and 12. The Western Ontario and McMasters University Osteoarthritis Index (WOMAC) pain score at baseline was 2.0, 1.8 after 2 weeks, and 1.7 after 12 weeks. This represented a 6% decrease in pain between weeks 2 and 12 (P = 0.42), with two subjects (11%) reported at least 30% pain relief between weeks 2 and 12 on the WOMAC. Effects on self-reported physical and role function and depression were marginal or non-significant, and observed physical function did not improve.

Conclusion: Venlafaxine significantly reduced pain intensity on the BPI and marginally improved self-reported function. Venlafaxine should be investigated further in a larger randomized trial for the treatment of osteoarthritis pain.