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Viral Load Levels in Therapy Determination

Comparing results from 2 assay methods

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Selection of patients for 8-week regimens on the basis of a single hepatitis C virus (HCV) RNA determination may not be reliable because viral load (VL) levels around the proposed clinical thresholds show significant interassay and intrapatient variability. This according to a study of pre- and on-treatment serum samples from 740 patients with HCV genotype-1 infection. Researchers found:

  • HCV RNA levels were significantly higher in analysis by CAP/CTM vs ART.
  • In treatment-naïve, noncirrhotic patients, discordance rates around the clinical cutoffs at 4M and 6M IU/mL were 23% and 18%, respectively.
  • Mean differences between assays in discordant samples were 0.38 (4M) and 0.41 (6M) log10 IU/mL, respectively.
  • Overall, 87% and 95% of treatment-naïve, noncirrhotic patients had a baseline HCV RNA below 4 and 6M IU/mL with ART.
  • These rates were significantly higher than those measured with CAP/CTM.
  • Discordance rates around the proposed thresholds in 2 consecutive samples were in the range of 1 to 2 % for ART and 13 to 17% for CAP/CTM.

Citation: Vermehren J, Maasoumy B, Maan R, et al. Applicability of HCV RNA viral load thresholds for 8-week treatments in patients with chronic hepatitis C genotype 1 infection. [Published online ahead of print February 9, 2016]. Clin Infect Dis. doi: 10.1093/cid/ciw061.

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