AEGiS-15IAC: Predictive value of total lymphocyte count (TLC) for disease progression in untreated HIV-infected children in Europe and USA.

3 for children " /> AEGiS-15IAC: Predictive value of total lymphocyte count (TLC) for disease progression in untreated HIV-infected children in Europe and USA.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Predictive value of total lymphocyte count (TLC) for disease progression in untreated HIV-infected children in Europe and USA.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. TuOrB1189)

Gibb DM, Dunn DT, Duong T, Galli L, Giaquinto C, Hughes M, Mofenson L, Moye J, Newell ML, Palumbo P, Rudin C, Shearer W
Medical Research Council Clinical Trials Unit, London, United Kingdom

BACKGROUND: TLC has been proposed as an alternative to CD4% for informing when to initiate antiretroviral therapy (ART) in HIV-infected children in resource-poor settings. WHO guidelines suggest a "threshold" of 2500 cells/mm³ for children<18 months and 1500 cells/mm³ for older children.

METHODS: Data from HPPMCS, a meta-analysis of ~4000 children enrolled in longitudinal studies in Europe and USA (Lancet 2003, 362:1605-11), were used to estimate the 12-month risk of death and AIDS (or death) as a function of most recent TLC and age. Estimates were obtained from parametric survival models, censoring data at initiation of ART (except zidovudine monotherapy).

RESULTS: For children >2 years, 12-month risk of death and of AIDS increase sharply at TLC values<1,500-2,000 cells/mm³, with a low and fairly stable risk at higher values. Younger children had a higher overall risk of progression and TLC was less prognostic. With reference to WHO guidelines, a 1-year old child with TLC=2500 cells/mm³ has an estimated 28% risk of AIDS within 12 months and 12% risk of death; the corresponding values for a 5-year old with TLC=1500 cells/mm³ are 14% and 5%. Statistically, TLC was a weaker predictor of death than CD4 percent, and the correlation between the two markers was low (r=0.09-0.25 within age groups). Discussion: Despite only a weak correlation with CD4%, TLC appears to be a useful prognostic marker in older children. However, as with other laboratory markers, it does not discriminate well between infants with a low and high risk of disease progression. Precise quantitative results should not be extrapolated to resource-poor settings, where clinical progression rates are much higher and white cell differentials may be less accurate. Analyses are ongoing to compare various "rules" utilising TLC and CD4% in the decision when to initiate ART.

Keywords: AEGIS, HIV, Acquired Immunodeficiency Syndrome, Disease Progression, HIV Seropositivity, Lymphocyte Count, HIV Infections, Anti-HIV Agents, Zidovudine, Forecasting, Antigens, CD4, Europe, Longitudinal Studies, Child, Humans, Infant, Ethics, immunology

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TuOrB1189