Effect of CD4+ cell count measurement variability on staging HIV-1 infection

Donald R. Hoover, Neil M. Graham, Baibai Chen, Jeremy M.G. Taylor, John Phair, Susan Y.J. Zhou, Alvaro Munoz

Research output: Contribution to journalArticlepeer-review

Abstract

A single CD4+cell count (CD4) measurement is often used to stage HIV-1 infection, decide when toinitiate prophylactic therapy and inform patients, and may soon even define AIDS onset. Documentation of the reliability and validity of employing CD4 for the above purposes in a population-based setting is needed. We utilized data from 4,954 homosexual/bisexual men fol- lowed over 6 years, with CD4 testing at 6 month intervals, to study the timing of CD4-based staging of HIV-I disease and quantify and evaluate the potential impact of CD4 measurement error. The median time from seroconversion to first CD4 test below 500 × 106/L or clinical AIDS was 1.70 years, and the first CD4 test below 200 × 106/L or clinical AIDs was 5.29 years. The time from first testing <500 × 6/L to clinical AIDS in untreated men was 5.55 years. With confirmatory retesting, these times were significantly lengthened. The 95% confidence ranges for the true CD4 state in individuals with measured CD4 of 500 and 200 x 6/L are at least (297 × 6, 841 × 6/L) and (118 × 6, 337 × 6/L), respectively. Without confirmatory retesting, individuals with true CD4 remaining at 700 × 6 and 280 × 6/L have at least a 40% chance for one of five CD4 measurements to fall below guideline limits of 500 × 6 and 200 × 6/L, respectively. Confirmatory retesting can reduce these probabilities to as low as 4%. These data suggest the following: (i) initiating antiretroviral therapy when the CD4 cell count is <500 × 6/L and defining AIDS by CD4 <200 × 6/L in certain circumstances may not be ideal; (ii) confirmatory retesting can significantly influence the timing and duration of therapy, and the time to CD4-defined AIDS; and (iii) confidence intervals should be calculated and reported along with point estimates for CD4 cell levels. This has significant prognostic, clinical, and economic implications.

Original languageEnglish (US)
Pages (from-to)794-802
Number of pages9
JournalJournal of Acquired Immune Deficiency Syndromes
Volume5
Issue number8
StatePublished - Aug 1992

Keywords

  • CD4 cells
  • Definition of aids
  • Human immunodeficiency virus type 1
  • Reproducibility of results
  • Sensitivity and specificity
  • Staging
  • Surrogate markers

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)

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