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Correlation among total lymphocyte count, absolute CD4+ count, and CD4+ percentage in a group of HIV-1-infected South
E van der Ryst1, M Kotze, G Joubert
1Department of Virology, University of the Orange Free State, Bloemfontein, South Africa. gnvrevdr@med.uovs.ac.za
Insights
Total lymphocyte count (TLC) can be a less expensive alternative to CD4+ T-cell counts for monitoring HIV-1. However, this study found TLC is not a reliable predictor of CD4+ T-cell counts in South African patients.
Area of Science:
- Immunology
- Infectious Diseases
- Public Health
Background:
- CD4+ T-cell depletion is a key indicator of HIV-1 progression.
- Accurate CD4+ T-cell counts are crucial for patient management but are often costly and inaccessible.
- Total lymphocyte count (TLC) has been proposed as a potential surrogate marker for CD4+ T-cell counts.
Purpose of the Study:
- To evaluate the relationship between total lymphocyte count (TLC) and CD4+ T-cell count in HIV-1-infected South African patients.
- To determine the predictive value of TLC for low CD4+ T-cell counts (<200 cells/mm3, <20%, <15%) in this population.
Main Methods:
- Analysis of 3237 observations from 2777 HIV-1-seropositive patients in Bloemfontein, South Africa (1991-1997).
- Calculation of sensitivity, specificity, and likelihood ratios for various TLC cutpoints to predict low CD4+ T-cell counts.
- Spearman rank correlations were computed between TLC and CD4+/CD8+ T-cell counts.
Main Results:
- A TLC of ≤2 x 10(9)/L showed 90.3% sensitivity but only 53.7% specificity for predicting CD4+ T-cell counts <200 cells/mm3.
- Lowering TLC cutoffs improved specificity but reduced sensitivity.
- A moderate correlation (r=0.704) between TLC and CD4+ T-cell count was observed for the entire group, but this weakened significantly when patients were stratified by CD4+ T-cell levels.
Conclusions:
- While TLC correlates with CD4+ T-cell count, it is not a sufficiently accurate predictor in this HIV-1-infected South African cohort.
- The use of TLC as a clinical tool for managing HIV/AIDS patients in this setting is not recommended due to its limited predictive value.
Abstract:
Depletion of CD4+ T cells is one of the hallmarks of progression of HIV-1 infection. However, measurement of the CD4+ T-cell count is expensive and often unavailable in less developed areas. Previous studies have suggested that the total lymphocyte count (TLC) can be used to predict a low absolute CD4+ T-cell count. To determine the relationship between TLC and CD4+ T-cell count in HIV-1-infected South African patients, 2777 HIV-1-seropositive patients visiting the Immunology clinic at the Pelonomi Hospital in Bloemfontein, South Africa from April 1991 to April 1997 were included in the study. In total, 3237 observations were used to determine sensitivity, specificity, and likelihood ratios, with 95% confidence intervals, of various cutpoints of the TLC to predict an absolute CD4+ T-cell count of <200 cells/mm3, CD4+ percentage <20%, and CD4+ percentage <15%. Spearman rank correlations were calculated between TLC and CD4+ T cells, CD4+ percentage and CD8+ T cells, as well as between CD4+ and CD8+ T cells. Results demonstrated that a TLC of 2 x 10(9)/L or less had a sensitivity of 90.3% to detect patients with a CD4+ T-cell count of <200 cells/mm3, but a specificity of only 53.7%. When the TLC cutoff value was lowered, specificity increased but sensitivity decreased. For the observations as a group, a correlation (r = 0.704) between CD4+ T-cell count and TLC was demonstrated, but if the patients were divided into three groups according to their CD4+ T-cell count, this correlation weakened considerably. Therefore, although TLC shows a correlation with CD4+ T-cell count, it is not a good predictor of the CD4+ T-cell count in this population and should preferably not be used in the clinical care of HIV/AIDS patients.