Postdoctoral Scholar Department of Pharmacy Practice and Science, University of Kentucky College of Pharmacy, Lexington, KY, United States, United States
Background: Buprenorphine treatment for opioid use disorder (OUD) reduces mortality, while with limited accessibility in rural communities compared to urban. Urban counties have higher drug overdose death rates, yet the urban-rural mortality differences in patients receiving buprenorphine medication for OUD treatment (MOUD) are not well understood.
Objectives: To examine urban-rural differences in mortality in patients receiving buprenorphine MOUD.
Methods: We used Kentucky state prescription monitoring data to identify adult Kentucky residents who initiated buprenorphine MOUD from 2017 to 2019. Patients were categorized as urban or rural residents based on residential ZIP code using the 2010 Rural-Urban Commuting Area codes. The cohort was followed for 365 days from the initiation day to capture deaths. The cause and date of death were obtained through linkage with Kentucky death certificate. Endpoints were all-cause death, opioid-involved overdose death, and death from causes other than opioid-involved overdose. The 365-day cumulative incidence was calculated for all-cause deaths, and the 365-day cumulative incidence function (CIF) were respectively calculated for opioid-involved overdose deaths and deaths from other causes. The association between urban/rural residency and each outcome were evaluated using a multivariable Cox regression model for all-cause deaths and multivariable Fine and Gray models for the other two outcomes with competing risks, adjusting for age, gender, and history of controlled substance use.
Results: The study cohort comprised 51,011 patients, with 65.8% from urban and 34.2% from rural areas. During the 365-day follow up, 234 opioid-involved overdose deaths and 449 deaths from other causes occurred. The 365-day cumulative incidence of all-cause death was 1.49% (95% Confidence Interval [CI]: 1.36%-1.62%) for urban patients and 1.06% (CI: 0.91%-1.21%) for rural patients. Urban patients had 50% higher all-cause deaths adjusted hazard ratio (aHR) (aHR: 1.50; CI: 1.27-1.78) than rural patients. The 365-day CIF of opioid-involved overdose deaths was 0.64% (CI: 0.56% to 0.73%) for urban patients and 0.12% (CI: 0.07% - 0.18%) for rural patients, with urban patients having an adjusted subdistribution hazard ratio of 5.72 (CI: 3.62-9.06) compared to rural patients. The 365-day CIF of deaths from other causes was 0.85% (CI, 0.76%-0.95%) and 0.94% (CI, 0.81%-1.09%) for patients from urban and rural areas, with no urban-rural difference in the multivariable Fine and Gray model (p=.816).
Conclusions: Urban patients receiving buprenorphine MOUD had higher incidences of all-cause and opioid-involved deaths despite easier treatment access. Further research is needed to understand causes for these disparities, including factors like treatment retention and fentanyl access.
