The risk of disease progression associated with a specific CD4 cell count or percentage varies with the age of
the child. Infants in the first year of life experience higher risks of progression or death than older children
for any given CD4 stratum. For example, comparing a 1-year-old child with a CD4 percentage of 25% to a 5-
year-old child with the same CD4 percentage, there is an approximately fourfold increase in the risk of AIDS
and six fold increase in the risk of death in the 1-year-old child (see Figures A and B in Appendix C:
Supplemental Information). Children aged 5 years or older have a lower risk of progression than younger
children, with the increase in risk of AIDS or death corresponding to CD4 cell count more similar to those in
young adults (see Figure C and Table B in Appendix C: Supplemental Information). In the HPPMCS, there
were no deaths among children aged 5 years or older with CD4 cell count >350 cells/mm3
, although in
younger children there continued to be a significant risk of death even with CD4 cell count >500 cells/mm3
(see Table B in Appendix C: Supplemental Information)