Reformulation of extended-release oxycodone may have triggered increase in hepatitis C rates

Interventions to deter opioid misuse may have unintended long-term public health consequences. Abuse-deterrent reformulations of extended-release oxycodone (OxyContin), introduced in 2010, may have led to more heroin use and higher rates of hepatitis C virus (HCV) infection, a study found.

Researchers looked at data from 2004 to 2015 to assess whether states with higher rates of OxyContin misuse before the reformulation experienced faster growth in infections afterward. They determined the rate of new HCV infections in each state using data from the CDC, which collects confirmed case reports from state and local health departments for the National Notifiable Diseases Surveillance System. States were then divided into two groups based on exposure to the reformulation: above-median initial rates of OxyContin misuse and below-median rates. Because patients in the first group were more exposed than those in the second group, researchers tested how this affected HCV infection rates after the reformulation. As a falsification exercise, they repeated the tests using misuse of prescription pain relievers such as hydrocodone, tramadol, and morphine. The study results were published in the February Health Affairs.

Between 2010 and 2015, OxyContin misuse decreased by more than 40%, while rates of heroin-related death and HCV infections increased sharply, the authors wrote. States with above-median OxyContin misuse before the reformulation experienced a 222% increase in HCV infection rates afterward, whereas states with below-median misuse experienced only a 75% increase. While HCV infection rates were not significantly different between the two groups of states before the reformulation (0.350 per 100,000 population vs. 0.260 per 100,000 population, respectively), afterward there were large and significant differences (1.128 per 100,000 population vs. 0.455 per 100,000 population, respectively; P<0.01). Above-median states experienced an additional 0.58 HCV infections per 100,000 population through 2015 compared with the below-median states.

The study authors noted that infections increased three times faster in states with above-median rates of initial OxyContin misuse than in states with below-median rates, and this increase began immediately after the reformulation in 2010. Before the reformulation, there was almost no difference in HCV infection rates across the two groups of states, they said.

“The unintended consequences of reformulation suggest that some caution is warranted in the implementation of other supply-side interventions that limit the supply of abusable prescription opioids,” the authors wrote. “Such interventions must be paired with policies that alleviate the harms associated with switching to illicit drugs, such as improved access to substance use disorder treatment and increased efforts aimed at identifying and treating diseases associated with injection drug use.”