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Opioid Maintenance Therapy Linked to Lower Hepatitis C Rates for People Who Inject Drugs

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Young drug injectors who undergo opioid agonist maintenance therapy using buprenorphine or methadone have a lower likelihood of becoming infected with hepatitis C virus (HCV) than those who continue injecting or use other types of substance use treatment, according to a study published in the October 27 edition of JAMA Internal Medicine.

HCV is readily transmitted through contact with blood, as can occur when people share needles, syringes, and other equipment for injecting drugs. As such, people who inject drugs have a high hepatitis C prevalence rate, with some recent studies showing a recent increase among young injectors.

Judith Tsui from Boston University School of Medicine and colleagues evaluated whether opioid agonist therapy is associated with a lower risk of HCV infection among young drug injectors.

Opioid agonists are agents such as buprenorphine or methadone that target the same brain receptors as opiates like heroin or prescription painkillers such as oxycodone. Agonists prevent opiate withdrawal symptoms but are longer lasting and typically do not produce a "high" when used at low doses for maintenance therapy.

Prior studies have found that opioid substitution therapy is associated with reduced HCV incidence among injection drug users overall, but little is known about younger drug users -- a group that is of particular interest because people tend to become infected with HCV soon after they start injecting.

The researchers conducted an observational cohort study between January 2000 and August 2013. The analysis included 552 injection drug users under age 30 (median age 23 years) in San Francisco who were negative for HCV antibodies or HCV RNA at study entry. Two-thirds were men, 73% were white, and 70% said they were homeless. The most commonly used drug was heroin, reported by nearly 60%. The median duration of drug use was 3.6 years and 33% said they were daily users.

The study compared people who underwent substance use treatment within the past 3 months including detoxification or maintenance therapy using buprenorphine or methadone, or non-opioid agonist forms of treatment, or no treatment. Most participants (82%) reported no treatment in the prior year, while 4% reported opioid agonist maintenance therapy and the remainder used other forms of treatment.

Results

  • A total of 171 new HCV infections occurred during an observation period of 680 person-years, for an overall incidence rate of 25.1 per 100 person-years.
  • Participants who reported recent opioid agonist therapy maintenance had a significantly lower rate of HCV infection (rate ratio 0.31; p=0.001).
  • There was no significant risk reduction, however, for participants who reported non-opioid agonist forms of treatment (rate ratio 0.63; p=0.09) or opioid agonist detoxification without maintenance (rate ratio 1.45; p=0.23).
  • After adjusting for other factors, opioid agonist maintenance therapy was associated with about a 60% lower relative risk for HCV infection over time (adjusted hazard ratio 0.39; p=0.02).

"Maintenance treatment with methadone or buprenorphine for opioid use disorders may be an important strategy to prevent the spread of HCV infection among young injection drug users," the study authors concluded.

"Young injection drug users are a major driving force in the epidemic of HCV infection in the United States and Canada and therefore are an important target for prevention," they elaborated. "Our results suggest that treatment for opioid use disorders with maintenance opioid agonist therapy can reduce transmission of HCV in young adult injection drug users and should be offered as an important component of comprehensive strategies for prevention of primary HCV infection."

10/28/14

Reference

JI Tsui, JL Evans, PJ Lum, et al. Association of Opioid Agonist Therapy With Lower Incidence of Hepatitis C Virus Infection in Young Adult Injection Drug Users. JAMA Internal Medicine. October 27, 2014 (Epub ahead of print).

Other Source

JAMA. Maintenance Opioid Agonist Therapy for Injection-Drug Users Associated with Lower Incidence of Hepatitis C. Media advisory. October 27, 2014.