A study by researchers at the Centers for Disease Control and Prevention (CDC) supports what public health investigators already have come to believe: The upsurge in cases of acute hepatitis C virus (HCV) infection is linked to the growing national opioid epidemic and increasing use of injection drugs.
The study, recently published in American Journal of Public Health, puts numbers to the crisis. From 2004 to 2014, the annual incidence rate of acute HCV infection increased by more than two-fold (133%), from 0.3 cases to 0.7 cases per 100,000 (P < 0.001).
During the same period, admissions to drug treatment facilities for injection drug use increased 76%, with an 85% increase for heroin injection and a nearly four-fold increase (258%) for prescription opioid injection.
“Taken together, these increases indicate a striking demographic convergence among opioid use or misuse, injection drug use, and acute HCV infection,” wrote CDC investigators.
Not just baby boomers any more
Although HCV is known to be common among baby boomers (Americans born between 1945 and 1965), increases in HCV incidence occurred in all age, gender, and race/ethnicity categories. But the largest increases were among 18- to 29-year-olds and 30- to 39-year-olds.
These increases in HCV infection paralleled increases in admissions to drug treatment facilities. For instance, 18- to 29-year-olds had a 400% increase in acute HCV infection, coupled with a 603% rise in admissions for heroin injection, and an 817% increase in admissions for injection of prescription opioid analgesics.
Thirty- to 39-year-olds had a 325% increase in acute HCV infection, with a 77% increase in admissions for heroin injection, and a 169% increase in admissions for injection of prescription opioids.
In almost every year from 2004 to 2014, injection drug use was involved in 60% or more reported HCV cases that included risk factor data—and the numbers have grown over time. From 2011 to 2014, the percentage increased to more than 75% of cases each year. In 2014 (the most recent year data were available), 84% of HCV cases that included risk factor data involved injection drug use.
State of the problem
“Our findings, which reveal national increases in both the number of persons injecting prescription opioid analgesics and the number of acute HCV infections, indicate a more widespread problem than previous studies have shown,” the authors wrote.
Of the 40 states that reported data for all years (2004-2014), 15 states had an increase over time of 500% or higher in the number of cases of acute HCV infection. Six states (Kansas, Maine, New Jersey, Wisconsin, Ohio, and Massachusetts) had increases of 1,000% or higher.
Only seven states (Delaware, North Dakota, Nevada, Texas, Vermont, South Carolina, and Michigan) reported decreases in the number of HCV cases during this period.
Among treatment admissions between 2004 and 2014, prescription opioid injection represented a higher percentage of admissions than heroin injection; however, heroin injection accounted for an overall greater percentage of the total number of admissions attributed to any opioid injection during this period.
“For example, admissions attributed to heroin injection constituted 18% of all treatment admissions in 2014, compared with 6% of admissions for prescription opioid injection,” investigators noted.
This statistic corresponds to reports that both first-time heroin use and the number of people reporting heroin dependency more than doubled by 2014.
“These findings offer further support that the increase in acute HCV infection is a sequela of the opioid epidemic and facilitated by an increase in the number of persons who inject drugs in substance use disorder treatment who report injecting heroin, prescription opioid analgesics, or both,” the authors concluded.
“A coordinated response among federal, state, and local health departments is essential to address the syndemic of opioid use and misuse and HCV infection on a national scale,” they recommended.