Characteristics of studies included in review, first CD4 cell count measurement after HIV diagnosis and mortality rates prior to initiation of antiretroviral therapy (ART).

n.r. not reported.*Immunological and clinical eligibility criteria for ART initiation were the following:WHO 2003 guidelines [33]: all children if WHO paediatric stage III.WHO paediatric stage I (only when CD4 count available) or paediatric stage II:≥18 months: CD4 percentage WHO 2006 guidelines [20]: all children if WHO stage 3 or 4 (there are specific rules for WHO stage 3 in case of co-infections).WHO stage 1 or 2 (total lymphocyte counts are used in sites where CD4 values cannot be determined):1 to 3 to ≥5 years: CD4 percentage • WHO 2010 guidelines [21]: all children if WHO stage 1 or 2:2 to ≥5 years: ≤350 cells/µl.WHO 2003 guidelines [33]: all children if WHO paediatric stage III.WHO paediatric stage I (only when CD4 count available) or paediatric stage II:≥18 months: CD4 percentage WHO 2006 guidelines [20]: all children if WHO stage 3 or 4 (there are specific rules for WHO stage 3 in case of co-infections).WHO stage 1 or 2 (total lymphocyte counts are used in sites where CD4 values cannot be determined):1 to 3 to ≥5 years: CD4 percentage • WHO 2010 guidelines [21]: all children if WHO stage 1 or 2:2 to ≥5 years: ≤350 cells/µl.**Absolute CD4 count A, percentage CD4 P.***Of 162 HIV exposed children, all 24 children who were diagnosed HIV positive were included.