The incidence of some of the most serious extrahepatic health problems caused by hepatitis C declines sharply after the infection is cured by antiviral treatment, a review of people treated for hepatitis C in the Canadian province of British Columbia has found.
The findings were presented by Carmine Rossi of the British Columbia Centre for Disease Control at the 2018 AASLD Liver Meeting in San Francisco on Sunday.
Hepatitis C infection is associated with a higher incidence of chronic kidney disease, diabetes and cardiovascular disease. Although the mechanisms leading to an increased risk of these conditions in people with hepatitis C are not fully understood, liver damage caused by hepatitis C is known to disrupt glucose metabolism. Chronic hepatitis C infection affects the cardiovascular system in numerous ways and also damages the kidneys.
Curing hepatitis C might reduce the incidence of these health problems, but the impact of treatment has been unclear. To investigate the extent to which hepatitis C treatment might reduce the burden of these conditions, researchers from the British Columbia Hepatitis Testers Cohort, the BC Centre for Disease Control and the University of British Columbia looked at the outcomes of 73,000 people who tested positive for hepatitis C between 1999 and 2014 in the province.
Of the 73,000, 9471 people were treated for hepatitis C using interferon-based treatment and had HCV RNA measurements available at least ten weeks after completing treatment. The study looked at outcomes in the interferon era rather than after the introduction of direct-acting antivirals because the study needed a sufficiently large population and duration of post-treatment follow-up to detect trends in outcomes that were statistically significant.
The researchers excluded all persons with an existing condition from analysis of post-SVR incidence of that condition.
A total of 5930 people achieved a sustained virological response. The only substantive difference between those who were cured and those who were not was age; the median age of the treatment cohort was 50 years, but a higher proportion of those who were not cured were born between 1945 and 1965 (79% vs 69%).
Approximately one-fifth of the treated cohort were people who inject drugs. Major mental illness was common in the cohort: 25% had a diagnosis of a major mental illness. Approximately one-fifth had hypertension, but diabetes was much less common: only 3% of those cured and 6% of those not cured had diabetes at the time of treatment.
After treatment the cumulative incidence of diabetes and mood and anxiety disorders rose most sharply. After ten years of follow-up, almost 13% of non-responders had developed diabetes (incidence rate 13 cases per 1000 person-years of follow-up) and just over 30% had developed a mood or anxiety disorder (44 cases per 1000 person-years). In comparison, rates of these disorders were 47% and 29% lower in people cured of hepatitis C.
Rates of several other conditions were also significantly lower in people who had been cured of hepatitis C. The incidence of stroke was 33% lower and the incidence of chronic kidney disease was 52% lower, although in both cases the overall incidence of the condition was much lower than the incidence of diabetes or mood disorder. The impact of cure on the incidence of stroke was statistically significant in people born between 1945 and 1965 but not in people born outside those years.
Being cured of hepatitis C did not affect the incidence of rheumatoid arthritis or ischaemic heart disease.
Carmine Rossi said that the large population studied make the findings generalisable to the entire HCV-infected population in care, and point to considerable reductions in healthcare resource utilisation.
Rossi C et al. Sustained virologic responses reduces the incidence of extrahepatic manifestations in chronic hepatitis C infection. AASLD Liver Meeting, San Francisco, abstract 0148, 2018.