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Evaluation of PIMA™® Point of Care Technology for CD4 T Cell Enumeration in Kenya
Published: Tuesday, June 25, 2013
Author: Matilu Mwau et al.

by Matilu Mwau, Ferdinard Adungo, Silvia Kadima, Ephantus Njagi, Carolyne Kirwaye, Najma Salim Abubakr, Lucy Atsieno Okubi, Mary Waihenya, Judi Lusike, Jackson Hungu

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™ (r2?=?0.762, mean bias -64.8 cells/µl), and the BD FACSCount™ (r2?=?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™ (r2?=?0.781, mean bias -24.2 cells/µl) and GUAVA™ (r2?=?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.