Do White People with HIV Lose CD4 Cells Faster than Blacks in the Absence of Antiretroviral Therapy?

		SUMMARY: Untreated white HIV patients experienced significantly larger decreases in CD4 cells than black patients in 2 very different settings -- Switzerland and South Africa -- according to a study reported in the December 1, 2009 Journal of Infectious Diseases. Steeper decreases were also associated with older age and higher initial CD4 count.

By Liz Highleyman

Many studies have looked at differences in HIV disease progression in people of various racial/ethnic groups, but results have been inconsistent and hard to interpret due to the difficulty of controlling for confounding factors such as access to care and overall health status.

While a growing body of evidence points to the benefits of early antiretroviral therapy (ART) -- potentially even at CD4 cell counts above 500 cells/mm3 -- it is also important to look at the natural history of HIV disease progression in individuals who do not receive timely treatment.

Margaret May from the University of Bristol and an international team of colleagues analyzed CD4 cell count decreases in 2 populations with a wide variation in standard of health of care: the Cape Town AIDS Cohort in South Africa and the Swiss HIV Cohort Study.

The analysis included 784 HIV positive participants in South African (of whom 155 were white and 629 were classified as "nonwhite") and 2030 participants in the Swiss cohort (1812 white and 218 nonwhite). In total, participants contributed 13,388 CD4 cell measurements.

The investigators used mixed-effects models and joint models to look at the correlation between CD4 cell decreases and survival, as well as stratified analyses with participants categorized according to initial CD4 count:

	50-199 cells/mm3;
	200-349 cells/mm3;
	350-499 cells/mm3;
	500-750 cells/mm3.

Results

	Decreases in CD4 cell count were steeper among white compared with nonwhite participants.
	CD4 cell decreases were also steeper among older patients and among people with higher initial CD4 counts.
	The smallest decrease was 38 cells/mm3, among nonwhite participants aged15-39 years with an initial CD4 count of 200-349 cells/mm3 in the Swiss cohort.
	The largest decrease was 210 cells/mm3, among white patients in the Cape Town cohort aged 40 years or older with an initial CD4 count of 500-750 cells/mm3.

The investigators concluded, based on these findings, "Among both patients from Switzerland and patients from South Africa, CD4+ cell count decreases were greater in white patients with HIV infection than they were in nonwhite patients with HIV infection."

The investigators were unable to clearly pinpoint a reason for these racial/ethnic differences, however, and recommended further research in this area.

University of Bristol, United Kingdom; Desmond Tutu HIV Research Centre, Institute of Infectious Disease and Molecular Medicine, and Infectious Diseases Epidemiology Unit, School of Public Health and Family Medicine, University of Cape Town, South Africa; Mailman School of Public Health, Columbia University, New York; Data Centre, Swiss HIV Cohort Study, Lausanne, Switzerland; University Hospital Inselspital, Bern, Switzerland; Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; University Hospital Basel, Basel, Switzerland.

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Reference

M May, R Wood, L Myer, and others. CD4(+) T Cell Count Decreases by Ethnicity among Untreated Patients with HIV Infection in South Africa and Switzerland. Journal of Infectious Diseases 200(11): 1729-1735 (Abstract). December 1, 2009.