Risk Factors for HCV Infection among Injection Drug Users

By Liz Highleyman

It is well known that sharing needles to inject drugs can transmit the hepatitis C virus (HCV), as well as the hepatitis B virus (HBV) and HIV. Two recent studies explored other risk factors for HCV infection among injection drug users (IDUs).

Study 1

In the first study, reported in the October 2006 issue of Addiction, Australian researchers aimed to determine the incidence of HCV infection among IDUs and to identify risk factors for seroconversion. In this prospective cohort study, participants were recruited through direct approaches, street-based outreach, methadone and sexual health clinics, and needle and syringe exchange and distribution programs in New South Wales.

A total of 584 IDUs were screened for exposure to HCV. Between 1999 and 2002, 368 HCV negative IDUs were enrolled and followed every 3-6 months until HCV seroconversion or study completion. Participants completed questionnaires asking about demographics, drug use, and risk behavior.

Results

During the follow-up period, 68 HCV seroconversions were observed, for an incidence rate of 30.8 per 100 person-years (PY).

Among participants who had been injecting drugs for less than 1 year, the incidence rate was more than 4 times higher, at 133 per 100 PY.

Independent predictors of seroconversion were:

- Female gender;
- Duration of injection;
- Injection of cocaine;
- Shared use of cotton or other material to filter drugs;
- Recruitment via street outreach.

Conclusion

In conclusion, the authors wrote, "Women, new initiates and IDUs recruited via outreach appear to be at increased risk of infection. Results confirm the significance of cocaine injection as a risk factor and provide the first evidence outside North America of the link between shared use of drug preparation equipment and incident HCV infection."

They added that, "Prevention efforts should attempt to raise awareness of the risks associated with drug sharing and, in particular, the role of potentially contaminated syringes in HCV infection."

Study 2

In the second study, researchers in Belgium estimated the independent risk of sharing drug injection equipment other than needles and syringes. In the August 2006 Journal of Viral Hepatitis, they reported that, "sharing of materials other than syringes/needles indeed seemed to contribute substantially to the spread of hepatitis C among injecting drug users."

Taken together, these studies suggest that prevention programs targeting IDUs should educate users about the risk of sharing drug preparation equipment such as filters, cookers, spoons, and rinse water, and that needle exchange and distribution programs should provide these items along with sterile syringes.

09/08/06

References

L Maher, B Jalaludin, K G Chant, and others. Incidence and risk factors for hepatitis C seroconversion in injecting drug users in Australia. Addiction 101(10): 1499-1508. October 2006.

C Mathei, Z Shkedy, B Denis, and others. Evidence for a substantial role of sharing of injecting paraphernalia other than syringes/needles to the spread of hepatitis C among injecting drug users. Journal of Viral Hepatitis 13(8): 560-570. August 2006.