Use
of ribavirin in combination with pegylated interferon reduces
the risk of HCV relapse and improves the likelihood of achieving
sustained virological response (SVR) to treatment for chronic
hepatitis C. Ribavirin doses are typically adjusted according
to weight, especially for people with HCV genotype 1, usually
ranging from 800 or 1000 to 1200 or 1400 mg/day.
Many previous studies have found that body weight or BMI predicts
treatment outcomes, with heavier people being less likely to achieve
SVR. While obesity and related metabolic problems are known to
have an effect on hepatitis C and liver health in general, poorer
treatment response among heavier patients may also indicate that
they did not receive enough ribavirin to do the job.
To further explore this issue, Jenny Heathcote from the University
of Toronto and colleagues conducted a study to determine whether
patient weight influences early viral kinetics (changes in HCV
levels soon after starting therapy) and subsequent SVR.
This retrospective analysis included 134 chronic hepatitis C patients
-- 57% with hard-to-treat HCV genotype 1 -- who received pegyalted
interferon plus ribavirin. The average BMI was 26.7 (classified
as overweight) and the average ribavirin dose was 13.9 mg/kg/day.
The researchers looked at HCV viral load measurements taken at
week 4 of treatment using 2 tests with different sensitivities.
The first RVR assessment used a PCR test with a limit of detection
of 50 IU/mL. Heathcote's team later re-tested stored blood samples
using the Taqman assay with a lower limit of 15 IU/mL.
Results
 |
Overall,
59% of study participants achieved SVR, or continued undetectable
HCV viral load 6 months after completing treatment. |
|
39.6%
of these patients achieved RVR at week 4 according to the
50 IU/mL test. |
|
Fewer
patients -- 27.6% -- achieved RVR according to the more
sensitive 15 IU/mL assay. |
|
Neither
body weight nor BMI influenced likelihood SVR or RVR by
either test. |
|
The
positive predictive value of RVR for SVR was 88.7% for the
50 IU/mL test and 97.3% for the 15 IU/mL test. |
|
RVR
according to either the 50 or 15 IU/mL cutoff was a better
independent predictor of SVR that HCV genotype and viral
load. |
"RVR
is the strongest predictor of SVR," the study authors concluded.
"Early viral kinetics is not influenced by body weight
or BMI when weight-based ribavirin is prescribed."
Investigator affiliations: Department of Medicine, Toronto Western
Hospital, University Health Network, Toronto, ON, Canada; University
of Sydney, Sydney, NSW, Australia; Division of Gastroenterology
and Department of Microbiology, Laboratory Medicine & Pathobiology,
Mt. Sinai Hospital, University of Toronto, Toronto, ON, Canada
1/25/11
Reference
V Pattullo, NC Ravindran, T Mazzulli, DK Wong, and EJ Heathcote.
Pegylated interferon plus optimized weight-based ribavirin dosing
negate the influence of weight and body mass index on early
viral kinetics and sustained virological response in chronic
hepatitis C. Journal of Viral Hepatitis 17(12): 834-838
(Abstract).
December 2010.
