Should absolute lymphocyte count be used as a surrogate marker for CD4+ count in patients with HIV/AIDS?

Abstract

The World Health Organization (WHO) has recommended The use of absolute lymphocyte count (ALC) as a potential marker for immunosuppression where CD4+ count is unavailable. However, there arc conflicting reports on the usefulness of ALC as a surrogate marker for CD4+ counts in patients with HIV/AIDS, more so. in patients with HIV associated tuberculosis (TB). To evaluate the usefulness of ALC as an alternative to CD4 + to count and to see whether TB affects the correlation of ALC with CD4+ counts in patients with HIV-associated TB. A total of 66 consecutive patients (33 with and 33 without TB) with a diagnosis of HIV infection were recruited into the study as cases Another group of 66 subjects (33 subjects each) age- and sex-matched HIV-negative controls were recruited as controls and stratified in to two: a) HIV-negativc PTB patients,b) apparently healthy HIV and PTB negative individuals' The age range was from 15-60 years (median: 32 years). The highest percentage (39%) of subjects fell in the age range of 25-29 years. The mean ALC for HIV-associated PTB was 3906 ± 1092 cclls/jil and for patients with HIV infection only. 4755 ± 1049 cells/ftl. There was no significant difference in mean ALC between males and females in both groups (Y^>().()5). Patients with dual infection by M. tuberculosis and HIV had the lowest mean ALC (3906 ± 1092cclls/|il). Healthy controls had mean ALC (±SD) of 5249±10I cells//fil. There was significant difference between the healthy controls and the other three groups. The observed difference was more in patients with HIV/TB co-infection (P<0.005) compared with patients with HIV alone (P<0.()5). No significant correlation was observed between CD4+ cell counts and ALC in all the age groups of the study population. When the CD4+ counts were divided into <200 and >200 cells/jil and the ALC into <2000 and >2000 cells/|il. the sensitivity, specificity and positive predictive values of the diagnostic usefulness of ALC in HIV-associated PTB were 52%. 56.3%and 78.8% while for HIV only patients the same values were 56.3%. 55.9% and 54.5%. . We cannot recommend the use of ALC as a surrogate for CD4+ count in our environment as this study has clearly shown that the correlation between the two is weak. Patients with dual infection by HIV and A/. tuberculosis arc more likely to have lower CD4+ cell and AL counts than those with HIV infection occurring alone.