Evaluation of PIMA™ CD4 system for decentralization of immunological monitoring of HIV-infected patients in Senegal

Background: HIV infection is a concern in the army troupes because of the risk behaviour of the military population. In order to allow regular access to CD4+ T cell enumeration of military personnel as well as their dependents and civilians living with HIV, the Senegalese Army AIDS program is implementing PIMA™ Alere technology in urban and semi-urban military medical centres. Validation such device is therefore required prior their wide implementation. The purpose of this study was to compare CD4+ T cell count measurements between the PIMA™ Alere to the BD FACSCount™. Methodology: We selected a total of 200 subjects including 50 patients with CD4+ T-cells below 200/mm3, 50 between 200 and 350/mm3, 50 between 351 and 500/mm3, and 50 above 500/mm3. CD4+ T-cell count was performed on venous blood using the BD FASCount™ as reference method and the PIMA™ Point of Care technology. The mean biases and limits of agreement between the PIMA™ Alere and BD FACSCount™ were assessed with the Bland-Altman analysis, the linear regression performed using the Passing-Bablok regression analysis, and the percent similarity calculated using the Scott method. Results: Our data have shown a mean difference of 22.3 cells/mm3 [95%CI:9.1-35.5] between the BD FACSCount™ and PIMA™ Alere CD4 measurements. However, the mean differences of the two methods was not significantly different to zero when CD4+ T-cell count was below 350/mm3 (P = 0.76). The Passing-Bablok regression in categorized CD4 counts has also showed concordance correlation coefficient of 0.89 for CD4+ T cell counts below 350/mm3 whilst it was 0.5 when CD4 was above 350/mm3. Conclusion: Overall, our data have shown that for low CD4 counts, the results from the PIMA™ Alere provided accurate CD4+ T cell counts with a good agreement compared to the FACSCount™.