on behalf of the Spanish Group of Pediatric HIV Infectiona

Background. Use of antiretroviral therapy has resulted in a decrease in morbidity and mortality rates in human immunodeficiency virus type 1 (HIV-1)–infected children. Methods. We performed a retrospective study involving 427 children to determine the effectiveness of different antiretroviral therapy protocols on clinical outcome. The follow-up period was divided into 5 calendar periods (CPs): CP1 (1980–1989), before antiretroviral therapy was administered; CP2 (1990–1993), when monotherapy was administered; CP3 (1994–1996), when combined therapy was administered; CP4 (1997–1998), when 50% of children were receiving highly active antiretroviral therapy (HAART); and CP5 (1999–2003), when 60 % of children were receiving HAART. Results. Children experienced a progressive increase in the CD4+ cell count and decrease in the viral load from 1997 onwards. A lower number of AIDS cases and deaths occurred during CP5 than during the other CPs (), with a relative risk of an absence of AIDS of 120 and a relative risk of survival of 130. The AIDS rateP!.01 was 150 % in CP1; we observed a very strong decrease to 14 % in CP2, to 16 % in CP3, to 7 % in CP4, and to 2% in CP5. The mortality rates in CP2 and CP3 were 16 % and thereafter decreased to 0.5 % in CP5. The relative risks for no hospital admission in CP4 and CP5 were 13.5. The total rates of hospital admission in CP1, CP2, and CP3 were 130%; we observed a decrease in CP4 and CP5. The duration of hospitalization decreased durin