[WeOrB1342] Successful implementation in West African laboratories of an alternative method to accurately enumerate at lower cost circulating CD4+ T lymphocytes in HIV-infected patients

14th International AIDS Conference

Barcelona, Spain — July 7-12, 2002

[TITLE:] Successful implementation in West African laboratories of an alternative method to accurately enumerate at lower cost circulating CD4+ T lymphocytes in HIV-infected patients

[AUTHOR(S):] S Diagbouga, P Van de Perre¹, C Chazallon², M D Kazatchkine³, A Inwoley⁴, S Mboup⁵, M Prince David⁶, A Tioro, R Soudré⁷

Int Conf AIDS. 2002 Jul 7-12;14:Abstract No. WeOrB1342

BACKGROUND: An international multicentric study was set to implement and validate a method (DynabeadsR), alternative to high-tech reference method (flow cytometry, FC) for measuring CD4 cell counts. This alternative method is based on CD4 T cell isolation using anti-CD4 mAB-coated magnetic beads.

METHODS: 657 pairs of values of CD4 cell counts have been obtained by both FC (TruCountR) and DynabeadsR from 684 blood samples of 301 HIV-infected patients seen in one (n=112), two (n=61), three (n=75), four (n=40) or five (n=13) occasions in 6 sites (Abidjan, Bamako, Bobo-Dioulasso, Dakar, Lome, Ouagadougou). Samples have been analyzed by 45 technicians. CD4 cell counts, measured by FC, were below 200/ml in 40.5% of samples, between 200 and 350 in 19.5%, 350 and 500 in 9.4%, 500 and 1000 in 20% and above 1000 in 10.5%.

RESULTS: The correlation coefficient between the 2 techniques was 0.89 (p<10-4). The overall median difference between DynabeadsR and FC was -16 cells/ml (p<10-4). Median difference, which was insignificant (+7.5 cells) for CD4 cell counts below 200, increased, in a non-linear fashion, with CD4 levels. Thus, median differences were -23 and - 43.5 cells for CD4 cell counts between 200 and 350 and between 350 and 500, respectively. In 88.7% of cases, patients were consistently classified at the threshold of 200 by both methods. Among 74 discrepant pairs of values, only 31 (4.7%, 95CI: 3.1-6.3) exhibited a difference of more than 100 cells. Analyses of individual longitudinal data suggested that the failing technique was DynabeadsR in 15 cases and FC in 11 cases.

CONCLUSIONS: DynabeadsR appeared to be a valid alternative to the reference method. The ability to consistently classify at thresholds of CD4 cell counts relevant to clinical care was close to 95%. Finally, the implementation of this method in 6 sites involving 45 technicians was easy and successful. Our results encourage the use of this alternative technique in countries with limited economic resources.

Presenting author: S Diagbouga

1Centre Muraz, Centre Muraz, BP390, Bobo-Dioulasso, Burkina Faso

2INSERM SC10, Villejuif, France

3Hôpital Européen Georges Pompidou, Paris, France

4CEDRES, Abidjan, Cote d'Ivoire

5Hôpital Le Dantec, Dakar, Senegal

6CHU campus, Lomé, Togo

7INRSP, Bamako, Mali; (8) Faculté de Médecine, Ouagadougou, Burkina Faso

020708
WeOrB1342