Comparison of safety outcomes among Caucasian, Hispanic, Black, and Asian patients in duloxetine studies of chronic painful conditions

Abstract

Objective: This post-hoc analysis was conducted to investigate if safety outcomes differed among race/ethnic subgroups of patients treated with duloxetine for chronic painful conditions.

Research design and methods: Pooled data from 15 placebo-controlled clinical trials were used to compare the safety outcomes of duloxetine among patients of Caucasian, Hispanic, Asian, and Black race/ethnic origins. Patients were randomized to receive placebo (n = 2199) or duloxetine (n = 3148) for treatment of diabetic peripheral neuropathic pain, fibromyalgia, osteoarthritis pain, or chronic low back pain. For categorical outcomes such as study discontinuation, adverse events leading to discontinuation, and treatment-emergent adverse events, incidence rates were summarized by race/ethnic subgroups. The Breslow-Day test was used to assess the homogeneity of treatment odds ratios across the four subgroups. For continuous outcomes such as changes in vital signs, body weight, and laboratory measures, an analysis of covariance or analysis of variance model was used and duloxetine effects were compared among race/ethnic subgroups based on the test of treatment-by-subgroup interaction.

Results: No significant differences were found among race/ethnic subgroups for discontinuation due to adverse events except for anxiety (p = 0.040). Rates of nausea and decreased appetite were significantly higher (p ≤ 0.05) in duloxetine-treated patients compared with placebo-treated patients within each race/ethnic subgroup. The Breslow-Day test was not significant for most safety outcomes, nor were treatment-by-race/ethnic subgroup interactions (p > 0.1), which suggested duloxetine effects were not significantly different among race/ethnic subgroups.

Conclusion: Overall, these results detected only minimal differences among safety outcomes assessed in these race/ethnic subgroups in patients treated with duloxetine for chronic painful conditions. The unbalanced sample sizes among the race/ethnic subgroups may have limited the power to detect treatment by race subgroup interactions. These post-hoc subgroup analyses were of an exploratory nature and the results should be interpreted with appropriate caution.