International CD4 Counting Multicenter Study
jharvey at guavatechnologies.com
Thu Jun 24 17:44:45 EST 2004
In the interests of providing additional coverage on this very important topic of reliable and affordable CD4 testing in resource poor countries, it should be noted that the results of two trials of the Guava EasyCD4 system and method were presented at the recent CROI meeting in San Francisco (Feb. 2004 -- abstracts available upon request). The results of two additional carefully controlled, multi-site trials will be made publicly available at the HIV/AIDS meeting in July (Bangkok). Trial results reveal that the CD4 counts obtained on the Guava system agree very well with the most commonly used predicate methods for performing this assay and at a fraction of the cost per test for reagents. An application note containing a description of the system and summarizing the method and the results of one of these trials is available from Guava Technologies, Inc.
Guava Technologies, Inc.
From: Roland Göhde [mailto:r.goehde at cytecs.com]
Sent: Friday, June 11, 2004 11:27 AM
Subject: International CD4 Counting Multicenter Study
I would like to inform you on a recently published international CD4 counting multicenter study which evaluates new alternatives for accurate and affordable HIV monitoring:
Cassens, U. et al: "Simplified volumetric flow cytometry allows feasible and accurate determination of CD4 T lymphocytes in immunodeficient patients worldwide", Antiviral Therapy 9:395-405 (2004) (ISI Impact Factor 6.57), International Medical Press 1359-6535/02
The abstract of this study is given as follows:
The determination of CD4 cells is of crucial clinical importance for patients with AIDS. However, the high costs involved represent limitations for CD4 cell counting in developing countries. In order to provide an affordable technique, we introduced a simplified volumetric counting (SVC) technique without sample manipulations and investigated it in a multicentre study. Blood samples from 434 healthy donors and immunodeficient patients were tested in eight hospital laboratories in Europe, Africa and Asia. CD4 cell counts were compared using in-house flow cytometric methods and the SVC technique. The SVC method was performed on a low-cost flow cytometer (CyFlow SL, Partec, Münster, Germany) after 15 min antibody incubation without pre-analytic manipulations, such as washing or erythrocyte lysing procedures. Linear regression analysis demonstrated a correlation of r=0.942 (Europe), r=0.952 (Africa) and r=0.989 (Asia) between the SVC technique and the in-house methods. Bland Altman plot analysis of all patient data showed a mean bias between the two methods of +26 CD4 cells in favour of the SVC technique (measured range: 6–1905 cells/µl; median CD4 cell count: 388/µl). Three centres used the FACS-count technique (Becton-Dickinson, San José, Calif., USA) as an in-house method dispensing with pre-analytic manipulations. The comparison of SVC and FACS-count method revealed a mean bias of +32 CD4 cells/µl (median CD4 cell count: 349/µl). The accuracy of the SVC was tested on standards with known CD4 cell counts (n=6) and was shown to be 95.2%. The low-cost device and the simplified no-lyse, no-wash test procedure reduces the costs per determination and facilitates the use of flow cytometry in developing countries.
HIV/AIDS Project Coordinator
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