Home Search Abstracts Browse Sessions Program Committee View Session E-mail Abstract Author

 

 

Session 126 Poster Abstracts
Simplifying CD4 Testing
Friday, 1:30 - 3:30 pm
Hall A


740    
A Simple, Low-cost CD4 Assay for Monitoring HIV-infected Individuals in Resource-limited-Settings: An Evaluation of Guava EasyCD4 Assay
Balakrishnan Pachamuthu*1, S Solomon1, M Janardhanan1, N Kumarasamy1, B Venkatakrishnan1, S Reddy1, A Liaquath1, A Cecelia1, G Kailasom1, T Panchacharam2, B Ramratnam3, K Mayer3, and T Flanigan3
1YRG CARE,Chennai, India; 2Univ of Madras, Chennai, India; and 3Brown Univ, Providence, RI, USA

Background:  The cost of the ART is decreasing rapidly but the cost of HIV monitoring with standard assay remains high. Serial measurements of absolute CD4 counts are used in resource limited-settings to determine patient treatments, response to therapy and disease progression. Hence, there is an urgent need to evaluate the accuracy and reliability of low-cost CD4 count assays.

Methods:  EDTA blood specimen from HIV-infected individuals (n = 110), the age ranging from 6 to 60 (median 35) years were studied using EasyCD4 (Guava) in comparison with standard flow cytometry (FACSCount). For reproducibility of the results, inter- and intrapersonal testing (n = 40) were done with three different technologists. The specimens (n = 30) stored at different duration and temperature were evaluated. The results were analyzed using SPSS, Release 10.0.05.

Results:  The intra-cluster correlation coefficient (ICC) of the CD4 testing with EasyCD4 was 99% (95% CI 98.5 to 99.3; p < 0.0001). The sensitivity, specificity, positive predictive value and negative predictive value of the EasyCD4 in enumerating absolute CD4 counts of < 200/µL were 100%, 97%, 95%, and 100%, respectively. Reproducibility of the results with each person using Guava in comparison to FACSCount were > 98% and the intrapersonal testing using Guava was > 95%. The ICC with aged specimen were as follows:  99% with 24 hours, 48 hours, 72 hours, and 96 hours and 97.4% with 120 hours) in comparison to 6 hours testing. The specimen storage in 2 different conditions (<2 5°C and ambient temperature) also did not affect the results significantly (within 6 hours; 99.4%, 24 hours; 98.3%, 48 hours; 98.5%, 72 hours; 98.7%, 96 hours; 99% and 120 hours; 98%).

Conclusions:  The EasyCD4 assay has strong correlation with the standard assay, FACSCount in enumerating CD4 counts. It is a low cost (< $2 per test), reproducible results, easy to perform, require micro-volume of specimen and generate minimal biowaste. Therefore, EasyCD4 could be considered for use in resource-limited settings.

Keywords: Low cost HIV Monitoring; CD4 T-Lymphocyte count; Resource-limited settings