Background:  Current treatment guidelines recommend ART for persons living with HIV/AIDS (PLWHA) when their CD4 count is ≤ 350 cells/µl. We estimated the number of PLWHA age 15 to 49 years old eligible for and receiving ART in the United States.

Methods:  Data were obtained from published reports and analysis of the Centers for Disease Control and Prevention’s (CDC’s) national HIV/AIDS surveillance system to estimate the number of PLWHA (age 15 to 49 years), number of persons living with AIDS (PLWA), mean ratio of persons living with HIV without AIDS (PLWH) to PLWA, proportion of PLWH without CD4 count results, proportion of PLWH with CD4 ≤ 350, proportion of newly diagnosed PLWH who progressed to AIDS within a year, and the number of undiagnosed PLWHA. We used Monte Carlo simulations to estimate the number and 95% confidence intervals (CI) for PLWHA eligible for ART. Data to estimate the number of PLWHA receiving ART were obtained from the CDC Adult/Adolescent Spectrum of HIV Disease (ASD), a medical record-based surveillance project in 10 U.S. cities that contains prospectively collected information from > 60,000 PLWHA from 1990 to June 2004. The proportion of eligible PLWHA who received ART in 2003 was derived from ASD data. We used this proportion to estimate the number of PLWHA “in care” and receiving ART in the United States.

Results:  The estimated number of PLWHA age 15 to 49 years old in the United States eligible for ART in 2003 was 480,000 (95% CI 441,000 to 519,000). Of these, 340,000 (95% CI 320,000 to 360,000) were estimated to be diagnosed and “in care.” The proportion of persons in ASD eligible for ART was 67% (95% CI 66%  to 68%), and of these eligible persons 79% (95% CI 78% to 80%) received ART. The estimated national number of persons who received ART in 2003 in this age group was 268,000 (95% CI 253,000 to 284,000).

Conclusion:  Using the largest set of national data available, we estimated that only 55% of eligible PLWHA age 15 to 49 years old are receiving ART in the United States, suggesting a substantial unmet health care need for this service. Validation of these estimates and examination of factors affecting availability, accessibility, and acceptability to ART are needed. The number of PLWHA eligible for and receiving ART can be better estimated when all HIV and AIDS case surveillance jurisdictions are integrated and new population-based clinical surveillance systems are established.

Keywords: antiretroviral therapy; population estimate; CD4 count