“Regional variation in opioid use may be attenuated when pharmaceutical-sponsored trials include care that is often standardized by protocols,” the researchers wrote. “Understanding such variation is important for global trials that sometimes include time to opioid use as an end point.”
The findings appeared in JAMA Oncology.
For the study, researchers collected data from phase 3 randomized clinical trials going back to Jan. 1, 2008, up until the present. Internal U.S. Food and Drug Administration databases were queried for relevant trials on metastatic prostate cancer patients. Data analyses were conducted from September 2018 to February 2019. Opioid use was compared by region through the use of logistic regression models, descriptive statistics, and χ2 tests. Adjusted analyses took into account patient age, presence of visceral disease, bony disease, and baseline Eastern Cooperative Oncology Group Performance Status score and pain score.
Final analysis included a total of 9,670 patients (mean [SD] age, 69.2 [8.3] years) from eight clinical trials in 46 countries. Compared to North American patients, the odds of opioid use were significantly lower in patients in Eastern Europe (adjusted odds ratio [aOR], 0.19; 95% confidence interval [CI], 0.16-0.22) and Asia (aOR, 0.31; 95% CI, 0.25-0.38). This outcome persisted even in the presence of moderate to high baseline pain levels (Eastern Europe: aOR, 0.16 [95% CI, 0.12-0.22]; Asia: aOR, 0.47 [95% CI, 0.29-0.79]). In an analysis of patients within North America, opioid use rates did not largely differ between the U.S. and Canada (aOR, 1.13; 95% CI, 0.93-1.37).
“This study found that, despite the clinical trial setting, opioid use appeared to vary by world regions, suggesting that this variability should be considered in international clinical trials,” the study authors wrote.