External quality assessment of point-of-care CD4 testing in Thailand and Southeast Asia

Accreditation and Quality Assurance - In recent years, the use of point-of-care (POC) CD4 testing technologies has increased dramatically in Thailand and other Southeast Asian (SEA) countries....     

Low-CD4+ T-lymphocyte blood samples for external quality assessment of CD4 testing in resource-poor settings

External quality assessment (EQA) of CD4 testing is important for clinically monitoring of patients with HIV/AIDS. EQA materials are limited to blood samples from normal blood donors with normal CD4+ T-lymphocyte levels. This study aimed to develop low-CD4+ T-lymphocyte blood samples for CD4 EQA. CD4+ T-lymphocyte-depleted blood samples were prepared using a magnetic bead separation technique. These CD4+ T-lymphocyte-depleted blood samples were mixed with undepleted whole blood samples to obtain low-CD4+ T-lymphocyte blood samples. The percentage and the number of CD4+ T-lymphocytes were determined using a flow cytometer. An evaluation study of this low-CD4+ T-lymphocyte blood sample was performed by sending to participating laboratories to investigate the potential use as CD4 EQA material. Our results showed that a magnetic separation technique could be used to prepare low-CD4+ T-lymphocyte blood samples. CD4+ T-lymphocytes in the low-CD4+ T-lymphocyte blood samples ranged from 15 % to 18 % and 160–300 cell/μl, respectively. In addition, CD4 testing of our low-CD4+ T-lymphocyte blood samples could be achieved following both the single- and the dual-platform flow cytometric approaches. A pilot EQA investigation revealed that the CV values of the number and percentage of CD4+ T-lymphocytes were 14 % and 10 %, respectively. Having the low-CD4+ T-lymphocyte blood samples in our CD4 EQA program should ensure reliability and credibility of CD4 testing in Thailand and other resource-poor countries.     

Long-term external quality assessment program for CD4+ T-lymphocyte enumeration in Thailand

The accuracy and reliability of CD4+ T-lymphocyte enumeration are crucial for HIV healthcare management. Thailand’s CD4 external quality assessment (EQA) program was implemented in 2003. This program aims to improve the quality of CD4 testing by providing the quality control material, remedial action, and technical training. In this article, the overall longitudinal performance of the participating laboratories from 2003 to 2015 is reported. The EQA blood samples were sent to the participating laboratories in Thailand and other Southeast Asian (SEA) countries. The participants were requested to enumerate CD3+ and CD4+ T-lymphocytes. The trimmed mean, standard deviation (SD), coefficient of variation (CV), and standard deviation index (SDI) of both fraction and number were calculated from the returned data. Our result indicated a continuously increasing number of participants. The response rate of 72 trials was 98 %. The outlier rates for the fraction and number of CD4+ T-lymphocytes were 3.3 % and 3.4 %, respectively. The average CV of the fraction and number of CD4+ T-lymphocytes was 7.1 % and 9.4 %, respectively. In addition, the analysis of our current EQA trial no. 072 revealed that more than 98 % of participating laboratories had SDI values between ?2 and +2 for both fraction and number of CD3+ and CD4+ T-lymphocytes. In conclusion, the implementation of the CD4 EQA program in Thailand and other SEA countries has led to a reduction in the variability of the results of the CD4 count between laboratories and a continuous improvement in laboratory performance.