Risk factors for opportunistic illnesses in children with human immunodeficiency virus in the era of highly active antiretroviral therapy

Objective: To examine the relationship between the use of highly active antiretroviral treatment (HAART) and the occurrence of opportunistic illnesses (OIs) among children perinatally infected with human immunodeficiency virus. Design: Prospective cohort study. Setting: Pediatric AIDS Clinical Trials Group 219C cohort. Participants: From September 15, 2000, to August 31, 2003, 1927 children perinatally infected with human immunodeficiency virus and receiving HAART were followed up. Main Exposures: Age at initiating HAART, duration of HAART use, CD4⁺ T-lymphocyte percentage, and human immunodeficiency virus 1 viral load. Main Outcome Measures: Incidence rates for Centers for Disease Control and Prevention OI category B and OI category C events were calculated. The association between main exposures and OI occurrence was estimated using proportional hazards regression. Results: Of 1927 subjects, 226 (12.7%) developed OIs during follow-up. Incidence rates were 4.99 per 100 person-years (95% confidence interval, 4.30-5.76) for first OI category B events and 1.47 per 100 person-years (95% confidence interval, 1.12-1.91) for first OI category Cevents. Duration of HAART use was not related to OI risk. Older age (age >10 years) at HAART initiation was associated with increased risk of a first OI (hazard ratio, 2.48; 95% confidence interval, 1.23-5.00) compared with initiating HAART in children younger than 2 years. This increased risk diminished after adjusting for CD4⁺ T-lymphocyte percentage and Centers for Disease Control and Prevention disease category at HAART initiation. More children with OIs than without OIs had a CD4⁺ T-lymphocyte percentage of less than 15% at HAART initiation (49.6% of children with OIs vs 23.7% of children without OIs), at enrollment (41.2% of children with OIs vs 7.7% of children without OIs), and at the end of follow-up (41.2% of children with OIs vs 8.3% of children without OIs). Conclusions: Opportunistic illnesses are occurring in the pediatric human immunodeficiency virus population in the HAART era, mainly in children with persistently low CD4⁺ T-lymphocyte percentages. Lack of a sustained response to HAART rather than age at or duration of HAART use is predictive of OI risk.