Estimation of CD4 T-lymphocyte counts from percent CD4 T-lymphocyte determinations in HIV-1-infected subjects in sub-Saharan Africa

The relationship between CD4 percent and CD4 count has been reported to be different in industrialized countries compared to sub-Saharan Africa, where often only the former is reliable. CD4 determinations from an open cohort of hotel workers in Dar es Salaam followed between 1990 and 1998 were evaluated. T-lymphocyte determinations were offered once a year to 190 HIV-1 seropositive, 80 seroconverters and 495 sex and age matched HIV-seronegative subjects. After log transformation of the CD4 percent and CD4 counts a good fit to a linear regression curve was found, R² 0.697. The CD4 percent corresponding to a CD4 count of 200 cells/mm³ was found to be 9.8%. CD4 percent determination can be useful to estimate CD4 counts, but needs to be locally standardized. The CD4 percent in Africa corresponding to AIDS defining CD4 counts seems to be lower than in the industrialized world.