Body Weight May Not Affect Hepatitis C Treatment if Ribavirin Dose Is Adequate

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Body Weight May Not Affect Hepatitis C Treatment if Ribavirin Dose Is Adequate

SUMMARY: Body weight or body mass index (BMI) were not significant predictors of sustained response to interferon-based therapy for chronic hepatitis C as long as patients received a sufficient weight-adjusted dose of ribavirin, according to a retrospective analysis published in the December 2010 Journal of Viral Hepatitis. Researchers also found that rapid virological response (RVR) at week 4 was a stronger predictor of treatment success than HCV genotype or viral load.

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, 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

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ReferenceV 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.

Source: www.hivandhepatitis.com

http://www.hepctrust.org.uk/news/2011/January/Body+Weight+May+Not+Affect+Hepatitis+C+Treatment+if+Ribavirin+Dose+Is+Adequate