title: Evaluation of PIMA™® point of care technology for CD4 T cell enumeration in Kenya.
abstract: CD4+ T cell enumeration is used to determine eligibility for antiretroviral therapy (ART) and to monitor the immune status of HIV-positive patients; however, many patients do not have access to this essential diagnostic test. Introducing point of care (POC) testing may improve access. We have evaluated Alere's PIMA™, one such POC device, against conventional CD4+ testing platforms to determine its performance and validity for use in Kenya. In our hands, Alere PIMA™ had a coefficient of variability of 10.3% and of repeatability of 175.6 cells/µl. It differed from both the BD FACSCalibur™ (r(2) = 0.762, mean bias -64.8 cells/µl), and the BD FACSCount™ (r(2) = 0.874, mean bias 7.8 cells/µl). When compared to the FACSCalibur™ at a cutoff of 350 cells/µl, it had a sensitivity of 89.6% and a specificity of 86.7% in those aged 5 years and over (Kw = 0.7566). With the BD FACSCount™, it had a sensitivity of 79.4% and a specificity of 83.4% in those aged 5 years and over (Kw = 0.7790). The device also differed from PARTEC Cyflow™ (r(2) = 0.781, mean bias -24.2 cells/µl) and GUAVA™ (r(2) = 0.658, mean bias -0.3 cells/µl) platforms, which are used in some facilities in Kenya. We conclude that with refinement, Alere PIMA™ technology has potential benefits for HIV-positive patients. This study highlights the difficulty in selecting the most appropriate reference technology for technical evaluations.
authors.affiliation: Kenya Medical Research Institute, Nairobi, Kenya. matilu.mwau@gmail.com
authors.forename: Matilu
authors.initials: M
authors.lastname: Mwau
authors.forename: Ferdinard
authors.initials: F
authors.lastname: Adungo
authors.forename: Silvia
authors.initials: S
authors.lastname: Kadima
authors.forename: Ephantus
authors.initials: E
authors.lastname: Njagi
authors.forename: Carolyne
authors.initials: C
authors.lastname: Kirwaye
authors.forename: Najma Salim
authors.initials: NS
authors.lastname: Abubakr
authors.forename: Lucy Atsieno
authors.initials: LA
authors.lastname: Okubi
authors.forename: Mary
authors.initials: M
authors.lastname: Waihenya
authors.forename: Judi
authors.initials: J
authors.lastname: Lusike
authors.forename: Jackson
authors.initials: J
authors.lastname: Hungu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology*; D002452:Cell Count / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007630:Kenya; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D055815:Young Adult