CD4 counts in resource-limited settings

A simplified low cost method for measuring absolute and percentage CD4 counts with flow cytometry is comparable to established commercial assays and is affordable for routine use in Africa and could improve clinical decision making in patients with HIV.

The research, published recently in the British Medical Journal, assesses a CD4 counting method using a CD4 and CD5 antibody combination with reduced blood and reagent volumes. Diagnostic accuracy was assessed by measuring the agreement of the index test with two other assays – TruCount and FACSCount. The clinical usefullness of the count obtained was investigated by comparing CD4 counts with the new WHO clinical staging for patients with HIV.

The study took place in Malawi, a country with an estimated one million people with HIV, out of a population of 12 million. Researchers carried out assays on 129 consecutive blood samples sent for CD4 counting from HIV-positive patients. Comparison of CD4 count staging was carried out on 253 consecutive new patients attending the antiretroviral clinic.

Malawi has had an antiretroviral programme running since 2004. By the end of 2007, more than 95 000 patients had started on free antiretroviral therapy in public sector clinics. A low cost measure of CD4 count will allow better treatment of these patients, as clinical criteria alone do not allow accurate assessment of the extent of HIV progression.

MacLennan CA et al. BMJ 2007; 335: 190

See the full text of the article here http://www.bmj.com/cgi/content/full/335/7612/190