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.
Something that has an
effect outside the liver, for example when viral hepatitis affects the kidneys
or causes depression.
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.