Testing HCV positive has a sustained impact on drug injecting behaviour

Diagnosis with hepatitis C virus (HCV) is associated with a sustained reduction in injecting drug use, according to Canadian research published in the online edition of Clinical Infectious Diseases. Each additional three months of follow-up was associated with a 10% reduction in the likelihood of injecting cocaine or heroin. Screening for HCV was also associated with a reduction in the likelihood of sharing syringes, not only for people diagnosed with HCV but also for individuals testing HCV negative.

“The main finding of this study is that notification of HCV test results and counseling is related to reductions in subsequent drug use behavior for PWIDs [people who inject drugs] learning that they recently contracted an HCV infection, but not for those who are uninfected,” comment the authors. “Reductions in drug use behaviors are likely to reflect a response to being informed about a recent seroconversion.”

The authors of an editorial that accompanies the study believe the results highlight “the importance of HCV testing as a catalyst for behavior change”.

Worldwide, injecting drug use is the main mode of HCV transmission. Canada is a case in point, where 83% of incident infections involve PWIDs. Harm-reduction programmes that provide access to clean needles and syringes, information about safer injecting practices, and screening for HCV and HIV, are the mainstay of HCV prevention in Canada and some other countries.

Investigators in Montreal wanted to see if testing for HCV had a sustained impact on injecting behaviours and alcohol use among PWIDs.

They therefore designed a longitudinal study involving 208 adults who were active injecting drug users and who were HCV negative at baseline. Every six months, participants were screened for HCV and answered questions about their recent injecting behaviours and use of alcohol. Post-test counselling and appropriate referrals were provided.

The majority of participants were male (83%), and their mean age was 34 years. The mean duration of follow-up was 30 months. During this time, participants contributed a total of 528 person-years of follow-up. A third of participants seroconverted for HCV, an incidence rate of 14.4 per 100 person-years. Individuals who seroconverted were significantly more likely than individuals who remained HCV negative to report injecting opioids (51 vs 22%, p < 0.001), cocaine (87 vs 63%, p = 0.004) and the sharing of syringes (39 vs 24%, p = 0.021) in the previous six months.

During follow-up, the proportion of participants who reported sharing syringes fell to very low levels, irrespective of HCV infection status.

Notification of a positive HCV test result was also associated with significant and sustained falls in the odds of reporting injecting cocaine or heroin. Each additional three months of follow-up was associated with a 10% reduction in reporting each of these injecting behaviours. However, injecting of heroin and cocaine remained unchanged among participants who tested HCV negative.

“Our results suggest that it is mainly the notification of the HCV positive status that induces the decrease in risk among PWIDs,” write the investigators. “There is no sustained change in risk among those who continue to be seronegative.”

Regardless of the result, there was no evidence that HCV screening had an impact on alcohol use. The authors believe this finding “should raise concern” as alcohol is associated with accelerated HCV disease progression.

“The change in injecting behaviors after testing for HCV that was observed in this study strongly supports the expansion of HCV testing,” write the authors of the editorial. “Future research is needed to elucidate which interventions or experiences promote safer or less injection drug use among persons testing positive for HCV.”