Duloxetine Versus Placebo in Patients With Chronic Low Back Pain: A 12-Week,Fixed-Dose,Randomized, Double-Blind Trial

This randomized, double-blind, placebo-controlled study assessed efficacy and safety of duloxetine in patients with chronic low back pain (CLBP). Adults (n = 401) with a nonneuropathic CLBP and average pain intensity of ≥4 on an 11-point numerical scale (Brief Pain Inventory [BPI]) were treated with either duloxetine 60 mg once daily or placebo for 12 weeks. The primary measure was BPI average pain. Secondary endpoints included Patient's Global Impressions of Improvement (PGI-I), Roland Morris Disability Questionnaire (RMDQ-24), BPI-Severity (BPI-S), BPI-Interference (BPI-I), and response rates (either ≥30% or ≥50% BPI average pain reduction at endpoint). Health outcomes included Short Form-36, European Quality of Life–5 Dimensions, and the Work Productivity and Activity Impairment questionnaire. Safety and tolerability were assessed. Compared with placebo-treated patients, duloxetine-treated patients reported a significantly greater reduction in BPI average pain (P ≤ .001). Similarly, duloxetine-treated patients reported significantly greater improvements in PGI-I, BPI-S, BPI-I, 50% response rates, and some health outcomes. The RMDQ and 30% response rate showed numerical improvements with duloxetine treatment. Significantly more patients in the duloxetine group (15.2%) than patients in the placebo group (5.4%) discontinued because of adverse events (P = .002). Nausea and dry mouth were the most common treatment-emergent adverse events with rates significantly higher in duloxetine-treated patients.