Evaluation of a low-cost method, the Guava EasyCD4 assay, to enumerate CD4-positive lymphocyte counts in HIV-infected patients in the United States and Uganda

Lisa A. Spacek, Hasan M. Shihab, Fred Lutwama, Jean Summerton, Harriet Mayanja, Allan Ronald, Joseph B. Margolick, Tricia L. Nilles, Thomas C. Quinn

Research output: Contribution to journalArticle

Abstract

Objective: To evaluate the EasyCD4 assay, a less expensive method to enumerate CD4+ lymphocytes, in resource-limited settings. Design: Cross-sectional study conducted in the United States and Uganda. Methods: We compared CD4+ cell counts obtained on replicate samples from HIV-infected patients by the EasyCD4 assay, a microcapillary flow-based system, and by standard flow cytometry or FACSCount with linear regression and the Bland-Altman method. Results: Two hundred eighteen samples were analyzed (77 in the United States and 141 in Uganda). In the United States, mean ± SD CD4 was 697 ± 438 cells/μL by standard flow cytometry and 688 ± 451 cells/μL by EasyCD4. In Uganda, the mean ± SD CD4 was 335 ± 331 cells/μL by FACSCount and 340 ± 327 cells/μL by EasyCD4. The 2 methods were highly correlated (US cohort, r2 = 0.97, slope = 1.0, intercept = -18; Ugandan cohort, r2 = 0.92; slope = 0.95; intercept = 23). The mean differences in CD4 cell counts were 9.0 and -4.6 cells/μL for the US and Ugandan cohorts, respectively, and they were not significant in either cohort. In the Ugandan cohort, sensitivity and specificity of the EasyCD4 for CD4 below 200 cells/ μL were 90% and 98%, respectively. Positive predictive value was 96%; negative predictive value was 93%. Conclusions: Our results suggest that EasyCD4 may be used with high positive and negative predictive value in resource-limited settings.

Original languageEnglish (US)
Pages (from-to)607-610
Number of pages4
JournalJournal of acquired immune deficiency syndromes
Volume41
Issue number5
DOIs
StatePublished - Apr 2006

Keywords

  • Antiretroviral therapy resource-limited setting
  • CD4-positive lymphocyte counts
  • Monitoring and evaluation
  • Uganda

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)

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