title: Multisite evaluation of a point-of-care instrument for CD4(+) T-cell enumeration using venous and finger-prick blood: the PIMA CD4.
abstract: BACKGROUND
  CD4(+) T-cell enumeration (CD4 count) is used as a criterion to initiate antiretroviral therapy (ART) in HIV patients and to monitor treatment efficacy. However, simple, affordable, and reliable point-of-care (POC) instruments adapted to resource-limited settings are still lacking. The PIMA CD4 analyzer is a new POC instrument for CD4 counting that uses disposable cartridges and a battery-powered analyzer.
  
  
  METHODS
  Whole blood samples were taken by venipuncture or by finger prick from 300 subjects, including HIV-infected patients and HIV (-) controls. CD4 counts were measured by PIMA (using venous or capillary blood) and by FACSCount (using venous blood) considered as the reference.
  
  
  RESULTS
  Similar CD4 counts were obtained by PIMA and FACSCount using either HIV+ venous blood or HIV+ finger-prick blood samples. However, with a concordance coefficient of 0.88 and a Pearson correlation of 0.89, finger-prick blood performed not as good as venous blood (0.97 and 0.98, respectively). For a clinical decision to start ART at 200 CD4 cells per microliter, sensitivity of PIMA was 90%/91% and specificity 98%/96% for venous/finger-prick blood, respectively, and for a treatment threshold of 350 CD4 cells per microliter, the sensitivity was 98%/91% and the specificity was 79%/80% for venous/finger-prick blood, respectively. Repeatability (precision) on venous blood resulted in a coefficient of variation of 4%. Using finger-prick blood, the average instrument error frequency resulting in aborted analyses was 14%.
  
  
  CONCLUSIONS
  PIMA is a good POC instrument for screening adult HIV-infected patients in resource-limited settings for treatment eligibility. Its performance on finger-prick blood is not as good as on venous blood. Adequate training for correct use of finger-prick blood samples is mandatory.
authors: Laboratoire de Bactériologie-Virologie, CHU Aristide le Dantec, Université Cheikh Anta Diop, Dakar, Sénégal. padiaw21@orange.sn
authors: Papa Alassane
authors: PA
authors: Diaw
authors: Géraldine
authors: G
authors: Daneau
authors: Abdoul Aziz
authors: AA
authors: Coly
authors: Birahim Pierre
authors: BP
authors: Ndiaye
authors: Djibril
authors: D
authors: Wade
authors: Makhtar
authors: M
authors: Camara
authors: Souleymane
authors: S
authors: Mboup
authors: Luc
authors: L
authors: Kestens
authors: Tandakha Ndiaye
authors: TN
authors: Dieye
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000295:instrumentation* / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000295:instrumentation* / Q000379:methods; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity