title: Technical performance evaluation of the MyT4 point of care technology for CD4+ T cell enumeration.
abstract: OBJECTIVE
  Though absolute CD4+ T cell enumeration is the primary gateway to antiretroviral therapy initiation for HIV-positive patients in all developing countries, patient access to this critical diagnostic test is relatively poor. We technically evaluated the performance of a newly developed point-of-care CD4+ T cell technology, the MyT4, compared with conventional CD4+ T cell testing technologies.
  
  
  METHODS
  Over 250 HIV-positive patients were consecutively enrolled and their blood tested on the MyT4, BD FACSCalibur, and BD FACSCount.
  
  
  RESULTS
  Compared with the BD FACSCount, the MyT4 had an r2 of 0.7269 and a mean bias of -23.37 cells/µl. Compared with the BD FACSCalibur, the MyT4 had an r2 of 0.5825 and a mean bias of -46.58 cells/µl. Kenya currently uses a CD4+ T cell test threshold of 350 cells/µl to determine patient eligibility for antiretroviral therapy. At this threshold, the MyT4 had a sensitivity of 95.3% (95% CI: 88.4-98.7%) and a specificity of 87.9% (95% CI: 82.3-92.3%) compared with the BD FACSCount and sensitivity and specificity of 88.2% (95% CI: 79.4-94.2%) and 84.2% (95% CI: 78.2-89.2%), respectively, compared with the BD FACSCalibur. Finally, the MyT4 had a coefficient of variation of 12.80% compared with 14.03% for the BD FACSCalibur.
  
  
  CONCLUSIONS
  We conclude that the MyT4 performed well at the current 350 cells/µl ART initiation eligibility threshold when used by lower cadres of health care facility staff in rural clinics compared to conventional CD4+ T cell technologies.
authors.affiliation: Kenya Medical Research Institute, Nairobi, Kenya.
authors.forename: Matilu
authors.initials: M
authors.lastname: Mwau
authors.affiliation: Clinton Health Access Initiative, Nairobi, Kenya.
authors.forename: Silvia
authors.initials: S
authors.lastname: Kadima
authors.affiliation: Kenya Medical Research Institute, Nairobi, Kenya.
authors.forename: Joy
authors.initials: J
authors.lastname: Mwende
authors.affiliation: Kenya Medical Research Institute, Nairobi, Kenya.
authors.forename: Maureen
authors.initials: M
authors.lastname: Adhiambo
authors.affiliation: Kenya Medical Research Institute, Nairobi, Kenya.
authors.forename: Catherine
authors.initials: C
authors.lastname: Akinyi
authors.affiliation: Clinton Health Access Initiative, Nairobi, Kenya.
authors.forename: Marta
authors.initials: M
authors.lastname: Prescott
authors.affiliation: Clinton Health Access Initiative, Nairobi, Kenya.
authors.forename: Judi
authors.initials: J
authors.lastname: Lusike
authors.affiliation: Clinton Health Access Initiative, Nairobi, Kenya.
authors.forename: Jackson
authors.initials: J
authors.lastname: Hungu
authors.affiliation: Clinton Health Access Initiative, Nairobi, Kenya.
authors.forename: Lara
authors.initials: L
authors.lastname: Vojnov
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000379:methods* / Q000592:standards; D005260:Female; D005434:Flow Cytometry / Q000379:methods / Q000592:standards; D015658:HIV Infections / Q000097:blood / Q000276:immunology; D006679:HIV Seropositivity; D006801:Humans; D007630:Kenya; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity