Objective: The objective of this study was to evaluate the effect of patients' characteristics at baseline on the magnitude of pain response to pregabalin in patients with fibromyalgia.
Methods: Data from four randomized, multicenter, placebo-controlled clinical studies of pregabalin in patients with fibromyalgia were used for the analysis. Approved doses (300 and 450 mg/day) were pooled to enhance the sensitivity of the interaction tests. A centered covariate interaction model was used to assess the treatment effects; a noncentered model was used for estimated mean pain changes and least square means across different levels of baseline covariates. The interaction was considered significant if p < 0.10.
Results: In total, 2061 patients (median age, 49 years; median pain score, 7.0; median duration of fibromyalgia, 83 months) were included in this analysis. No significant interaction was observed between treatment and anxiety, depression, or duration of fibromyalgia. Significant treatment by baseline mean pain (p = 0.037), treatment by baseline sleep score (p = 0.071), and treatment by age (p = 0.051) interactions were observed.
Conclusion: The magnitude of response to pregabalin in terms of changes in pain may depend on age, pain, and sleep levels at baseline in patients with fibromyalgia.