Background
Hepatitis C (HCV) infection causes cirrhosis and liver cancer, imparting substantial health risk. New pharmaceuticals, available since 2016, cure HCV and should improve outcomes. This linked data study determined which demographic factors differentially impact on morbidity and mortality in HCV notifications compared with matched controls in NSW, pre-2016.
Methods
The case cohort included all NSW HCV notifications (2005-2015). The control cohort, one-to-one matched on age-group, sex, remoteness and SEIFA score at baseline was selected from notifications un-associated with liver damage. Comorbidity histories and follow-up outcomes (all-cause death and liver-related hospital admissions) were identified for both groups from linked admissions and death data to mid-2017. Group-specific event incidence rates were calculated within levels of each demographic characteristic. Interaction terms within Cox regression models determined which demographic characteristics had a differential impact on outcomes in cases versus controls.
Results
A total of 30,053 HCV notifications were matched to controls. The unadjusted admissions rates were 6.7 and 0.2 events per 1000 person-years in HCV and control notifications respectively. For all-cause death they were 12.9 and 5.9. Age, comorbidities and SEIFA were significantly associated with differentials in time-to all-cause death in HCV compared to controls. Comorbidities were significantly associated with differentials in time-to-admission.
Conclusion
Risk of both outcomes was elevated in HCV notifications compared with matched controls. The differentials in time-to-death varied between HCV and controls with age, comorbidities and SEIFA while differentials in time-to-admission varied with comorbidities only. This study forms the baseline for ongoing surveillance of outcomes in HCV notifications post-2016.