Prevalence and knowledge of hepatitis C in a middle-aged population, Dunedin, New Zealand

To determine the prevalence of infection with hepatitis C virus (HCV) in those most at risk of advanced liver disease and to identify gaps in knowledge of HCV.

Questionnaires were mailed to randomly selected residents aged 40-59 to assess the extent of their general knowledge about HCV. The questionnaire assessed demographics, the extent of general knowledge about viral hepatitis, potential risks for infection and the prevalence of risk factors associated with increased progression of liver fibrosis. Anonymised residual laboratory blood samples from 40-59 years old people from Dunedin taken in hospital or in the community, were tested for HCV antibodies and alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transpeptidase (GGT). Linear regression was performed to examine whether the demographics sex, age, socio-economic status, qualification level and occupation sector (categorical variables) were predictors of level of general knowledge about hepatitis. For the demographics that were found to be significant predictors of score outcome, multiple regression analysis was used to determine independent effects. χ (2) tests were used to compare our selected sample and our responder population demographics, to the demographics of the entire 40-59 years old population in Dunedin using the 2006 NZ census data. Exact confidence intervals for the proportion positive for HCV and HBV were calculated using the binomial distribution.

The response rate to the mailed questionnaire was 431/1400 (30.8%). On average 59.4% questions were answered correctly. Predictors for higher scores, indicating greater knowledge about symptoms and transmission included sex (female, P < 0.01), higher level of qualification (P < 0.000) and occupation sector (P < 0.000). Sharing intravenous drug utensils was a known risk factor for disease transmission (94.4%), but the sharing of common household items such as a toothbrush was not. 93% of the population were unaware that HCV infection can be asymptomatic. 25% did not know that treatment was available in New Zealand and of those who did know, only 40% assumed it was funded. Six hundred and eighty-two residual anonymised blood samples were tested for HCV antibodies, ALT, AST and GGT. The prevalence for HCV was 4.01%, 95%CI: 2.6%-5.8%. Liver function tests were not useful for identifying likelyhood of HCV infection.

Prevalence of HCV in our population is high, and the majority have limited knowledge of HCV and its treatment.