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.

Keywords::

• Chronic pain
• Clinical trial
• Duloxetine
• Ethnic groups
• Safety

Transparency

Declaration of funding

Funding was provided by Eli Lilly and Company; Eli Lilly was involved in study design, analysis and interpretation of data, writing of the report and the decision to submit the paper for publication.

Declaration of financial/other relationships

P.J.G., P.L., and M.M.W. are employees and stockholders of Eli Lilly and Company. M.A.W. is an employee of inVentiv Health, working under contract with Eli Lilly and Company.

CMRO peer reviewers may have received honoraria for their review work. The peer reviewers on this manuscript have disclosed that they have no relevant financial relationships.

Acknowledgment

The authors thank Ms. Yanfang Pang of inVentiv Health Clinical, working under contract with Eli Lilly and Company, for her SAS programming support for the statistical analyses presented in this paper.