INTRODUCTION: Effective point-of-care testing (POCT) is reliant on optimal specimen collection, quality assured testing, and expedited return of results. Many of the POCT are designed to be used with fingerstick capillary blood to simplify the blood collection burden. However, fingerstick blood collection has inherent errors in sampling. An evaluation of the use of capillary and venous blood with CD4 POCT was conducted. METHODS: Three different specimen collection methods were evaluated for compatibility using the Alere Pima CD4 assay at 5 HIV/AIDS healthcare sites in Dar es Salaam, Tanzania. At each site, whole blood specimens were collected from enrolled patients by venipuncture and fingerstick. Pima CD4 testing was performed at site of collection on venipuncture specimens (Venous) and fingerstick blood directly applied to a Pima CD4 cartridge (Capillary-Direct) and collected into an EDTA microtube (Capillary-Microtube). Venous blood was also tested at the laboratory by the reference CD4 method and Pima for comparison analysis. RESULTS: All three specimen collection methods were successfully collected by healthcare workers for use with the Pima CD4 assay. When compared to the reference CD4 method, Pima CD4 testing with the Capillary-Microtube method performed similarly to Venous, while Pima CD4 counts with the Capillary-Direct method were slightly more biased (-20 cells/muL) and variable (-229 to +189 cells/muL limit of agreement). Even though all three collection methods had similar invalid Pima testing rates (10.5%, 9.8%, and 8.3% for Capillary-Direct, Capillary-Microtube, and Venous respectively), the ability to perform repeat testing with Capillary-Microtube and Venous specimens increased the likelihood of acquiring a valid CD4 result with the Pima assay. CONCLUSIONS: Capillary blood, either directly applied to Pima CD4 cartridges or collected in an EDTA microtube, and venous blood are suitable specimens for Pima CD4 testing. The advantages of capillary blood collection in an EDTA microtube are that it uses fingerstick collection which mimics venous blood and allows extra testing without additional blood collection.

INTRODUCTION: Point-of-care (POC) CD4 testing can improve access to treatment by enabling decentralization and reducing patient loss-to-follow-up. As new POC CD4 technologies become available, their performance should be assessed before widespread deployment. This study reports the findings of five independent evaluations of the PointCare NOW CD4 system. MATERIALS/METHODS: Evaluations were conducted in Southern Africa (Mozambique, South Africa) and North America (Canada, USA). 492 blood samples (55 from HIV-negative blood donors and 437 from HIV-infected patients, including 20 children aged between 12 and 59 months) were tested with both the PointCare NOW and reference flow cytometry instruments. Assessment of bias, precision and levels of clinical misclassification for absolute and percent CD4 count was conducted. RESULTS: PointCare NOW significantly overestimated CD4 absolute counts with a mean relative bias of +35.0%. Bias was greater in samples with CD4 counts below ≤350cells/microl (+51.3%) than in the CD4 >350cells/microl stratum (15.1%). Bias in CD4% had a similar trend with an overall relative mean bias of +25.6% and a larger bias for low CD4 stratum (+40.2%) than the higher CD4 stratum (+5.8%). Relative bias for CD4% in children was -6.8%. In terms of repeatability, PointCare NOW had a coefficient of variation of 11%. Using a threshold of 350cells/microl, only 47% of patients who qualified for antiretroviral therapy with reference CD4 testing, would have been eligible for treatment with PointCare NOW test results. This was 39% using a 200cells/microl threshold. Agreement with infant samples was higher, with 90% qualifying at a 25% eligibility threshold. CONCLUSION: The performance of the PointCare NOW instrument for absolute and percent CD4 enumeration was inadequate for HIV clinical management in adults. In children, the small sample size was not large enough to draw a conclusion. This study also highlights the importance of independent evaluation of new diagnostic technology platforms before deployment.

Quality assurance (QA) is a systematic process to monitor and improve clinical laboratory practices. The fundamental components of a laboratory QA program include providing a functional and safe laboratory environment, trained and competent personnel, maintained equipment, adequate supplies and reagents, testing of appropriate specimens, internal monitoring of quality, accurate reporting, and external quality assessments. These components are necessary to provide accurate and precise CD4 T-cell counts, an essential test to evaluate start of and monitor effectiveness of antiretroviral therapy for HIV-infected patients. In recent years, CD4 testing has expanded dramatically in resource-limited settings. Information on a CD4 QA program as described in this article will provide guidelines not only for clinical laboratory staff but also for managers of programs responsible for supporting CD4 testing. All agencies involved in implementing CD4 testing must understand the needs of the laboratory and provide advocacy, guidance, and financial support to established CD4 testing sites and programs. This article describes and explains the procedures that must be put in place to provide reliable CD4 determinations in a variety of settings.