Characteristics and Trends of NIH-Funded Opioid Use Disorder Clinical Trials During the Opioid Epidemic With a Focus on Gender

Objectives This study aims to analyze all funding awarded by the National Institute of Health (NIH) for opioid use disorder (OUD) clinical trials during the opioid epidemic and investigate whether there exist a difference in funding based on gender of principal investigators (PIs) and the wave of the opioid epidemic during which the trial began. Methods NIH-funded clinical trials related to OUD during the opioid epidemic between March 1, 1997, and February 28, 2023, were extracted from ClinicalTrials.gov and NIH RePORTER. Data extracted from each project included grant type, grant category, grant funding amount, and the PI's affiliation, academic rank, highest degrees, and gender. Non-parametric statistical analysis was performed using Kruskal-Wallis testing to investigate for discrepancies in NIH funding between genders and waves of the opioid epidemic. Results A total of 197 trials were identified as funded during the opioid epidemic, for a total of $1,646,512,558. Of the grants, 85.8% (N=169) were awarded during the third wave of the opioid epidemic; they received a median of $2,482,291 per year, significantly more than the second wave (p=0.0045). Male PIs (54.3%, N=107) received the highest number of grants, but they did not receive significantly more funding compared to female PIs (p=0.8646). A statistically significant difference in funding between the waves (p=0.0015) was found, with projects starting during the third wave receiving more average yearly funding (N=169) than the first two waves (N=28). Conclusion NIH funding amount and number of projects funded increased throughout the third wave of the opioid epidemic, potentially due to increased NIH initiatives during this time. Unlike other documented trends outlining disparities in funding between male and female researchers in academic medicine, there was no statistical difference in funding for clinical trials during the opioid epidemic. Further analysis is needed to ensure a diverse research landscape and determine areas for future improvement.