People living with HIV with previous hepatitis C virus (HCV) infection continue to have an
increased risk of chronic kidney disease, results of a North American study
published in the online edition of the Journal
of Infectious Diseases show.
The incidence of serious chronic kidney
disease was similarly elevated for people who had cleared HCV infection and
those with ongoing HCV viral replication. Both groups also had a similar risk
of experiencing kidney disease progression.
found that prior HCV infection was associated with excess CKD [chronic kidney
disease] risk irrespective of the presence or absence of HCV viremia
[detectable viral load],” comment the authors. “Our results suggest that
chronic HCV viremia is not the primary factor mediating increased CKD risk in
HIV-infected persons with prior HCV exposure.”
Between a quarter
and a third of people living with HIV in the United States also have HCV (co-infection). Epidemiological data suggest that infection with HCV is linked to an
increased risk of chronic kidney disease and renal failure in both the general
population and individuals with HIV.
A proportion of people spontaneously clear HCV infection and HCV can also be cured with
antiviral treatment. A team of investigators from the United States and Canada
wanted to explore the association between chronic HCV infection – ongoing HCV
replication – and the risk of chronic kidney disease.
compared the incidence of kidney disease in a cohort of 63,000 people
according to HCV exposure status: negative for HCV antibodies (HCV uninfected);
ongoing HCV replication (viraemic); antibodies to HCV but no detectable HCV
viral load (aviraemic).
glomerular filtration rate (eGFR) was used as a marker of chronic kidney
disease. People with eGFR below 60/ml/min/1.73m2 were defined as
having moderate kidney disease; eGFR below 15/ml/min/1.73m2 was
defined as severe kidney disease; and progressive kidney disease was defined as
a 25% reduction in eGFR from a baseline above 60/ml/min/1.73m2
lasting 60 or more days.
All the study participants
received care after 1996. Most – 52,602 – had never been infected with HCV;
9508 were HCV viraemic; and 913 had antibodies to HCV but no viral replication.
The participants had a
median age of 42 years and 41% were black. Just over a third (35%) had a
suppressed HIV viral load and the median CD4 cell count was 340 cells/mm3.
There was a high
prevalence of risk factors known to be associated with chronic kidney disease.
Overall, a quarter of participants had hypertension (high blood pressure), 5% were diabetic and
approximately a fifth had a history of injecting drug use. The authors
controlled for these factors in their statistical analysis.
people who had never had HCV, individuals with ongoing HCV
replication had an increased risk of moderate chronic kidney disease (adjusted
HR, 1.36; 95%, 1.26-1.46), serious chronic kidney disease (adjusted HR, 1.95;
95% CI, 1.64-2.31) and progressive renal disease (adjusted HR, 1.31; 95% CI,
People with antibodies
to HCV but no viral replication were also more likely to develop serious renal
disease compared to HCV-negative people. There was an association of
borderline significance between past HCV infection and progression to moderate
chronic kidney disease (adjusted HR, 1.19; 95% CI, 0.98-1.45), and significant
associations with progression to serious chronic renal disease (adjusted HR,
1.69; 95% CI, 1.07-2.65) and progressive chronic kidney disease (adjusted HR,
1.31; 95% CI, 1.02-1.68).
the HCV-viraemic and -aviraemic participants in the study showed that both groups had a similar
risk of each of the three study outcomes.
between current and past HCV infection and the progression of chronic kidney
disease remained robust in a series of sensitivity analyses.
“We found that
HIV-infected individuals with prior HCV co-infection were at risk for moderate
and advanced CKD, regardless of the presence of HCV viremia,” conclude the
authors. “The mechanism behind CKD risk in aviremic subjects is unclear, but
may include confounding effects from drug use, poorer control of HIV infection,
lower socioeconomic status, or other unidentified factors.”