Prevalence of chronic hepatitis B in South Western Sydney: evaluation of the country of birth method using maternal seroprevalence data

Abstract

To estimate the prevalence of hepatitis B infection and evaluate the country of birth (Census) method of describing hepatitis B distribution in an Australian health service with a large migrant population. The prevalence of chronic hepatitis B in Sydney South West Area Health Service (SSWAHS, population 1.3 million) was estimated by applying the prevalence of hepatitis B surface antigen (HBsAg) in high or intermediate hepatitis B prevalence countries to SSWAHS residents from those countries, using 2006 Census data. The Australian hepatitis B prevalence (0.7%) was applied to the remainder. This method was validated using HBsAg seroprevalence in 42,274 women aged 15-44 years who delivered at SSWAHS public maternity hospitals during 2007 to 2009. The SSWAHS prevalence of HBsAg using the Census method was 2.0% for all ages and 2.3% for 15-44 year old women. The seroprevalence in 15-44 year old mothers was 1.8%. The adjusted population prevalence was 1.6%. The two methods produced broadly similar descriptions of relative hepatitis B burden by local government area and country of birth. The Census method overestimates the prevalence of hepatitis B infection by 30%, but produces similar patterns of hepatitis B burden across the area. Health services can estimate the prevalence and distribution of chronic hepatitis B using readily available data to focus delivery of prevention and treatment services.