Mortality among British Columbians testing for hepatitis C antibody, 1992-2004

Background: Hepatitis C virus (HCV) infection is a major preventable and treatable cause of morbidity and mortality. The ability to link records between population-based centralized laboratory HCV testing data and administrative databases has provided a unique opportunity to compare mortality and morbidity between HCV seronegative and seropositive individuals. Through the use of laboratory testing patterns and results, this study attempts to differentiate the viral effects of mortality due to HCV infection from risk behaviours/activities that are associated with acquisition of HCV infection. Methods: Serological testing data at the British Columbia (BC) Centre for Disease Control from 1992-2004 were linked to the death registry at the BC Vital Statistics Agency. Four groups of HCV testers were defined by their HCV antibody (anti-HCV) testing patterns: single non-reactive (SNR); serial multiple tested non-reactive (MNR); reactive at initial testing (REAC); and seroconverter (previously seronegative followed by reactive, a marker for incident infection) (SERO). Standardized mortality ratios were generated to compare all-cause and disease specific mortality with the BC population. Time-dependent Cox proportional hazard regression was used to compare hazard ratios among HCV serological groups. Results: Anti-HCV testers were found to have higher mortality than the BC population. Referent to the SNR group, the REAC group had higher risks for liver-related mortality (hazard ratio (HR): 9.71, 95% confidence interval (CI): 8.62-10.87) and drug-related mortality (HR: 13.51, 95% CI: 11.63-15.63). When compared to the REAC group, the SERO group had a lower risk for liver-related mortality (HR: 0.53, 95% CI: 0.24-0.92), but a higher risk for drug-related mortality (HR: 1.60, 95% CI: 1.20-2.08). Conclusions: These findings confirm that anti-HCV positive testers have increased mortality due to chronic infection related to progressive liver disease, and that a substantial proportion of the mortality is attributable to drug use and risk behaviours/activities associated with HCV acquisition. Mortality reduction in HCV infected individuals will require comprehensive prevention programming to reduce the impact of mental health and problematic substance use behaviours/activities which relate to HCV acquisition, as well as HCV treatment to prevent progression of chronic liver disease.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat