Risk of hepatitis C virus infection in injecting and noninjecting drug users receiving opioid substitution therapy.

Background: Hepatitis C virus (HCV) is the most common viral infection among illicit drug users in the world. Although intervention of needle and syringe program and opioid substitution therapy had engaged to prevent HCV infection, the prevalence of HCV infection does not seem to decline. The aim of this study was to estimate the risk of HCV infection in injecting drug users (IDUs) and noninjecting drug users (NIDUs) receiving opioid substitution therapy.

Methods: We recruited 1179 heroin-dependent patients (age: 20-66 years) under opioid substitution therapy from 2012 to 2015 in a Psychiatric Center, Southern Taiwan. The data of HCV, hepatitis B virus and HIV infection and liver biochemical examination were obtained. We used multivariate logistic regression analysis to predict the risk of HCV infection.

Results: There were 93.1% of IDUs and 68.1% of NIDUs positive for HCV infection. In IDUs, HIV infection, age of heroin initiation, duration and dose of heroin use, frequency of detoxification, and number of criminal conviction were significantly associated with HCV infection. In NIDUs, snort/sniff heroin exhibited a significantly increased risk of HCV infection. Intravenous injecting (odds ratio [OR] = 23.10, 95% CI = 8.04-66.40, p < 0.001), intravenous injecting combined snort/sniff (OR = 12.95, 95% CI = 3.90-42.97, p < 0.001), and snort/sniff (OR = 4.14, 95% CI = 1.30-13.18, p = 0.016) were significantly associated with increased risk of HCV infection compared with smoking. The trend was significant (p for trend <0.001).

Conclusion: In Taiwan, IDUs had harmful characteristics compared with NIDUs and both had extremely high prevalence of HCV infection. We provided evidence that snort/sniff is a possible way of leak in HCV infection despite needle-syringes supplement program been provided. Opioid substitution therapy program should include HCV assessment and treatment in the new direct-acting antiviral therapy era.