How reliable is an undetectable viral load?

HIV Med. 2009 Sep;10(8):470-6. doi: 10.1111/j.1468-1293.2009.00714.x. Epub 2009 May 6.

Abstract

Objectives: An article by the Swiss AIDS Commission states that patients with stably suppressed viraemia [i.e. several successive HIV-1 RNA plasma concentrations (viral loads, VL) below the limits of detection during 6 months or more of highly active antiretroviral therapy (HAART)] are unlikely to be infectious. Questions then arise: how reliable is the undetectability of the VL, given the history of measures? What factors determine reliability?

Methods: We assessed the probability (henceforth termed reliability) that the n+1 VL would exceed 50 or 1000 HIV-1 RNA copies/mL when the nth one had been <50 copies/mL in 6168 patients of the Swiss HIV Cohort Study who were continuing to take HAART between 2003 and 2007. General estimating equations were used to analyse potential factors of reliability.

Results: With a cut-off at 50 copies/mL, reliability was 84.5% (n=1), increasing to 94.5% (n=5). Compliance, the current type of HAART and the first antiretroviral therapy (ART) received (HAART or not) were predictive factors of reliability. With a cut-off at 1000 copies/mL, reliability was 97.5% (n=1), increasing to 99.1% (n=4). Chart review revealed that patients had stopped their treatment, admitted to major problems with compliance or were taking non-HAART ART in 72.2% of these cases. Viral escape caused by resistance was found in 5.6%. No explanation was found in the charts of 22.2% of cases.

Conclusions: After several successive VLs at <50 copies/mL, reliability reaches approximately 94% with a cut-off of 50 copies/mL and approximately 99% with a cut-off at 1000 copies/mL. Compliance is the most important factor predicting reliability.

MeSH terms

  • Adult
  • Anti-HIV Agents / therapeutic use*
  • Antiretroviral Therapy, Highly Active / methods
  • CD4 Lymphocyte Count
  • Cohort Studies
  • Drug Resistance, Viral
  • Female
  • HIV Infections / drug therapy*
  • HIV Infections / immunology
  • HIV Infections / transmission
  • HIV Infections / virology
  • HIV-1 / drug effects
  • HIV-1 / genetics
  • HIV-1 / isolation & purification*
  • Humans
  • Male
  • Medication Adherence
  • Middle Aged
  • Multivariate Analysis
  • Probability
  • RNA, Viral / blood
  • Reproducibility of Results
  • Switzerland
  • Viral Load / drug effects
  • Viral Load / methods*
  • Viremia / diagnosis*
  • Viremia / virology

Substances

  • Anti-HIV Agents
  • RNA, Viral