Theme: Epidemiology & Public Health Research Year: 2017
Background The majority of individuals (95%) who acquire a hepatitis B virus (HBV) infection during adulthood, spontaneously clear the virus. However, we previously showed that shortly after infection, an unexpectedly high proportion (25.0%) of men who have sex with men (MSM) and people who use drugs (PWUD) develop chronic HBV. Therefore, we determined the presence, frequency and time to delayed clearance and, explored determinants hereof.
Methods We used data from PWUD and MSM the Amsterdam Cohort Studies who acquired HBV during follow-up. We defined three groups of HBV infection 1) Standard clearance: HBV surface-antigen (HBsAg) negative within 6 months of HBV seroconversion (HBVsc) 2) Delayed clearance: HBsAg positive within 6 months of HBVsc followed by a HBsAg and HBV-DNA negative result 3) Chronic infection: HBsAg positive, or HBsAg negative and HBV-DNA positive at their last visit. Potential determinants for delayed clearance and chronic HBV were examined using univariable multinomial logistic regression. Time to clearance was estimated using Kaplan-Meier method.
Results During follow-up, 148 individuals seroconverted for HBV (61 MSM, 87 PWUD). At HBVsc, 62.1% and 20.7% of all PWUD were HCV-monoinfected and HIV/HCV-coinfected, respectively, whereas 47.5% of MSM were HIV-monoinfected. De remainder of PWUD and MSM were HIV/HCV-uninfected. Standard clearance, delayed clearance and chronic HBV were observed in 71.0%, 10.4% and 18.2% of all individuals, respectively. Median time to clearance was 0.61 years. Among group 2 and 3, by 5 years since HBVsc, 42.6% (95%CI=22.0-56.3%) had cleared HBV. Younger age and HIV/HCV-coinfection were associated with delayed clearance and chronic infection; while ethnicity, risk group and gender were not.
Conclusion A substantial proportion of PWUD and MSM categorized as having a chronic HBV infection 6 months of HBV seroconversion, were able to spontaneously clear HBV thereafter. These findings should be incorporated in HBV screening and follow-up guidelines for these key populations.
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