Background/Purpose: Global trial data demonstrate the efficacy of pregabalin for the treatment of pain associated with fibromyalgia (FM), but there are currently no approved medical treatments for FM-related pain in China.

Methods: A phase 3, 14-week, multicenter, randomized, double-blind, flexible-dose, parallel-group, placebo-controlled trial was conducted in China (Feb 2012–Oct 2016) to assess the efficacy and safety of pregabalin in Chinese patients with FM. Eligible patients were aged ≥18 years, met the American College of Rheumatology 1990 criteria for FM, and had a mean numeric daily pain rating scale score of ≥4 (0=‘no pain’ to 10=‘worst possible pain’; 24-hr recall period) over a 7 day baseline period. Patients were randomized (1:1) to receive pregabalin (dosed twice daily) or matching placebo as follows: 1-week screening/placebo run-in, 2-week dose titration (150 mg/day titrated to 300–450 mg/day, based on efficacy and tolerability), 12-week fixed dose, and 1-week taper. Treatment allocation used a computer-generated pseudorandom code and the random permuted blocks method. The primary endpoint was change from baseline to endpoint (Week 14) in mean pain score analyzed using a mixed-model repeated measures (MMRM) approach; weekly mean pain scores were also evaluated using MMRM. Secondary endpoints included the percentage of patients with ≥30% and ≥50% reduction in endpoint mean pain score, Patient Global Impression of Change (PGIC), Fibromyalgia Impact Questionnaire (FIQ) total score, and measures of sleep. Adverse events (AEs) were also reported.

Trial registration: ClinicalTrials.gov Identifier: NCT01387607

Results: In total, 343 patients were randomized and 334 (86% female; average age 44 years) were treated (170 pregabalin, 164 placebo). Reduction in mean pain score was significantly greater with pregabalin than placebo at endpoint (least square mean difference [95% confidence interval], –0.73 [–1.10, –0.36]; P=0.0001) and at every week during the study (P<0.05) (Fig 1). Pregabalin treatment improved the percentage of patients achieving ≥30% (P=0.0044) and ≥50% (P=0.0189) reduction in pain score over placebo at endpoint. Pregabalin, compared with placebo, also significantly improved sleep interference score (P<0.0001). There was no statistically significant improvement in PGIC, FIQ total score and the Medical Outcomes Study–Sleep Scale sleep disturbance score at endpoint with pregabalin versus placebo. The most commonly reported AEs in the pregabalin vs placebo groups were dizziness (41.8% vs 18.3%), somnolence (17.6% vs 7.9%), headache (5.9% vs 6.1%) and upper respiratory tract infection (5.9% vs 4.3%), consistent with the safety profile of pregabalin.

Conclusion:

Pregabalin was effective in reducing pain compared with placebo and is well tolerated in Chinese patients with FM.

This study was sponsored by Pfizer.