Evaluation of PIMA(TM) registered Point of Care Technology for CD4 T Cell Enumeration in Kenya. e67612

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(TM), one such POC device, against conventional CD4+ testing platforms to determine its performance and validity for use in Kenya. In our hands, Alere PIMA(TM) had a coefficient of variability of 10.3% and of repeatability of 175.6 cells/ mu l. It differed from both the BD FACSCalibur(TM) (r2 = 0.762, mean bias -64.8 cells/ mu l), and the BD FACSCount(TM) (r2 = 0.874, mean bias 7.8 cells/ mu l). When compared to the FACSCalibur(TM) at a cutoff of 350 cells/ mu l, 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(TM), 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(TM) (r2 = 0.781, mean bias -24.2 cells/ mu l) and GUAVA(TM) (r2 = 0.658, mean bias -0.3 cells/ mu l) platforms, which are used in some facilities in Kenya. We conclude that with refinement, Alere PIMA(TM) technology has potential benefits for HIV-positive patients. This study highlights the difficulty in selecting the most appropriate reference technology for technical evaluations.