In 2010, OxyContin was reformulated and an abuse-deterrent version was introduced, leading to an increase in heroin use and subsequent rise in hepatitis C infection rates.
After declining during the 1990s and plateauing in 2003, hepatitis C infections have been sharply increasing since 2010. Between 2010 and 2015, the rate of new acute hepatitis C infections in the United States nearly tripled, and according to a new study, this spike has been fueled by unintended consequences of a reponse to the opioid epidemic.
In 2010, OxyContin was reformulated and an abuse-deterrent version was introduced. “The abuse-deterrent version of OxyContin uses physiochemical barriers to make the pill difficult to crush or dissolve, thus deterring the most dangerous methods of abuse of inhalation or injection,” explained the researchers. “Prior studies have shown that after OxyContin became more difficult to abuse, some nonmedical users of OxyContin switched to heroin.”
According to the researchers, this shift to heroin, which is associated with higher injection use relative to other drugs, can explain the increased exposure and incidence of hepatitis C, as it is a blood-borne infection that can be transmitted through shared needle use.
Drawing on data from the CDC, the researchers obtained data on acute hepatitis C infections from 2004 through 2015. They also used self-reported data from the public-use National Survey on Drug Use and Health, which offered state-level data on nonmedical drug use.
Between the reformulation in 2010 and 2015, there was a more than 40% drop in OxyContin misuse. During the same period, there were sharp jumps in both heroin-related mortality and hepatitis C infections, suggesting that that factors driving the rise in heroin deaths may also be driving the rise in hepatitis C infections, according to the researchers. Prior to the reformulation of OxyContin, hepatitis C infection rates were comparable between above- and below-median misuse states. However, following the reformulation in August 2010, the gap began to widen.
“The gap between states with above- and below-median misuse widened more rapidly beginning in 2011—the first full year after reformulation—and continued to increase through 2013,” wrote the researchers. “This striking inflection point in the trend of hepatitis C infections for high-misuse state after 2010 mimics the inflection in heroin overdoses that occurred as a result of the reformulation.”
By 2015, there was a 222% increase in hepatitis C infection rates in above-median initial misuse states compared with the pre-reformulation period (2004-2009). Meanwhile, states with below-median initial misuse experienced a 75% increase.
To confirm that OxyContin misuse was the driver of these increases, the researchers replicated the analysis but split the states into groups based on initial pain reliever misuse, excluding Oxycontin. This analysis revealed that after 2010, the 2 groups’ rates of hepatitis C infections grew at nearly identical rates.
“Our findings to not rule out the possibility that other factors, such as changes in the availability of prescription opioids or increased availability of inexpensive heroin from Mexico, may have independently contributed to the national rise in hepatitis C infection rates,” noted the researchers. “However, after we controlled for some of the likely alternative causes, we still found that the reformulation played an independent and important role.”
Powell D, Alpert A, Pacula R. A transitioning epidemic: how the opioid crisis is driving the rise in hepatitis C [published online February 4, 2019]. Health Aff. doi: 10.1377/hlthaff.2018.05232.