Hepatitis C Virus Re-infection in Injection Drug Users

Some past research has suggested that spontaneous clearance of hepatitis C virus (HCV) may provide protection against re-infection.

To test this hypothesis, researchers from British Columbia conducted a large community-based cohort study of 3.553 inner-city residents, most of whom were injection drug users. They identified HCV-infected individuals with virological clearance, and compared the rate of re-infection in this group with the infection rate observed in previously uninfected members of the same cohort.

Results

The researchers identified 658 HCV-infected subjects with detectable HCV RNA at baseline.

152 of 658 (23.1%) spontaneously cleared the virus over a median follow-up period of 5.2 years (IQR 2.8-7.4 years).

The comparison group included 926 individuals without HCV infection.

At baseline, individuals with HCV clearance were more likely to be HIV coinfected (P < 0.001) and to be engaged in frequent illicit drug use (P = 0.004) and injection drug use (P < 0.001).

The occurrence of new HCV infection was lower in individuals with previous infection (14 of 152; 9.2%) compared to those without previous infection (172 of 926; 18.6%.

Re-infection and infection rates were 1.8 and 8.1 cases per 100 person-years, respectively.

In a logistic regression analysis controlling for other potential confounding variables (age, sex, race/ethnicity, HIV coinfection, housing status, and illicit and injection drug use), individuals with previous HCV infection and viral clearance were 4 times less likely to be re-infected than previously uninfected subjects were to be infected for the first time (adjusted odds ratio 0.23; 95% CI 0.10-0.51; P < .001).

Conclusion

In conclusion, the authors wrote, "individuals with clearance of HCV infection may have a lower risk of acquiring HCV than individuals who have never been infected, despite ongoing exposure to HCV."

12/15/06

Reference
J Grebely, B Conway, J D Raffa, and others. Hepatitis C virus reinfection in injection drug users. Hepatology 44(5): 1139-1145. November 2006.