Objective: To determine the incidence and risk factors of HCV infection among heroin addicts who were receiving methadone maintenance treatment(MMT)in Dehong prefecture, Yunnan province.
Methods: All heroin addicts who were HCV negative at the initiation of MMT in June 2005 through March 2012, in Dehong prefecture, were included in this cohort analysis. HCV incidence was calculated and related risk factors determined by using Cox proportional hazard regression model.
Results: A total of 2390 MMT clinic attendants were qualified for this cohort study by March 2012. 731(30.6%) of them had never received any follow-up HCV testing so were recognized as loss to follow-up. The other 1659 (69.4%) participants had received at least one follow-up HCV testing and were observed for a total of 3509.12 person-years(py). During this period 99 new HCV infections or HCV sero-converters were identified. The overall HCV incidence was 2.82/100 py and was 3.62/100 py for 2006, 5.36/100 py for 2007, 6.71/100 py for 2008, 2.56/100 py for 2009, 1.90/100 py for 2010, and 0.44/100 py for 2011, respectively. Results from multiple regression analysis, using Cox proportional hazard model, indicated that after controlling for confounding variables, those who were unemployed, being injecting drug users(IDUs)or HIV positive at entry into the MMT program were more likely to be newly infected with HCV or HCV sero-converted during the follow-up period than those who were peasants, non-IDUs or HIV negative at entry into the MMT program(HR = 2.02, 95% CI:1.18-3.48; HR = 9.05, 95% CI:5.49-14.93; HR = 2.12, 95% CI: 1.37-3.56), respectively.
Conclusion: The incidence of HCV infection among MMT clinic attendants was decreasing since 2009 in Dehong prefecture. Those who were unemployed, injecting drug users and HIV positive were at higher risk of HCV infection.