People with hepatitis C remain at higher risk of chronic
kidney disease after clearing or being cured of hepatitis C and people with
genotype 1 infection have a higher risk of kidney disease before and after
being cured of hepatitis C, a large US study has reported.
The study investigators say that people who have been cured
of hepatitis C need to be recognised as having a higher risk of chronic kidney
disease and monitored accordingly.
Hepatitis C virus can cause kidney damage by several
mechanisms, including inflammation of blood vessels and over-production of
immune system proteins called cryoglobulins that can block small blood vessels.
A protein made in the liver, needed to maintain a balance of the fluids in the body. In a blood test, lower than normal levels of albumin and total protein may indicate liver damage or disease. If there is not enough albumin, fluid may accumulate in the abdomen (ascites).
Previous studies have shown that the risk of chronic kidney
disease and acute kidney failure is higher in people with hepatitis C than the
general population, but these studies have not explored whether people who have
been cured of hepatitis C have a similar risk of kidney disease as people who
still have the virus.
It’s also unclear if the risk of chronic kidney disease is
affected by hepatitis C genotype, as studies have produced conflicting results.
Researchers in Taiwan used data from the US National Health
and Nutrition Examination Study (NHANES) to analyse the risk of chronic kidney
disease in a large study cohort representative of the US population.
The study cohort consisted of 44,998 people included in
NHANES surveys between 1999 and 2018 who had records of kidney function and
hepatitis C antibody and RNA testing. Those with HCV antibodies and a negative
HCV RNA result were defined as having resolved hepatitis C (either spontaneously
cleared or cured by treatment).
The cohort consisted of 44,157 people without hepatitis C,
255 with resolved hepatitis C and 586 with chronic hepatitis C.
People with hepatitis C (including resolved hepatitis C)
were older (51 vs 46 years), more often male, more likely to have high blood pressure,
to have cardiovascular disease or a previous history of stroke, chronic hepatitis
B and HIV. The prevalence of albuminuria, a sign of kidney damage, was higher
in people with hepatitis C but there was no difference in the rate of reduced
Fifteen per cent of the entire study population had kidney
disease, defined as reduced kidney function (eGFR < 60 ml/min/1.73m2)
or a urinary albumin/creatinine ratio greater than 30mg/g. The prevalence of kidney
disease was higher in people with resolved kidney disease (23.5%) and chronic
HCV (20%). Multivariable analysis showed that the risk of chronic kidney disease
was 40% higher in people with resolved HCV and 26% higher in people with chronic
HCV after adjusting for age, sex, race, body mass index, diabetes, high blood
pressure, cardiovascular disease stroke and HIV.
Diabetes, cardiovascular disease, hypertension and HIV were
each more substantial risk factors for chronic kidney disease than hepatitis C,
raising the risk by between 60 and 150%.
In 586 people with detectable HCV RNA, 62% had genotype 1
infection, 8.5% genotype 2, 9% other genotypes and 19% had a missing genotype
result. Twenty-three per cent of people with genotype 1 had chronic kidney disease
compared to 12% of those with genotype 2 and 7% of those with other genotypes. People
with genotype 1 had a 41% higher risk of chronic kidney disease compared to
those without hepatitis and were more than twice as likely to have chronic kidney
disease compared to people with other genotypes.
The study did not find that the risk of kidney disease
increased in later periods but the investigators say that more research is
needed to detect whether sofosbuvir-based treatment has any negative impact on
kidney disease risk in people who have been cured of hepatitis C.