Background: Time of initiation of antiretroviral therapy (ART) has been an important issue due to its impact on morbidity and mortality.  Current treatment guidelines recommend initiating ART at CD4 <350.  The purpose of this analysis was to determine when patients initiated ART by CD4 count, factors associated with initiation, and to assess which initial regimen patients were prescribed.

Methods: Data were from the Adult/Adolescent Spectrum of HIV Disease (ASD) project.  We observed patients in 10 U.S. cities between 1996 and 2000 prescribed ART following enrollment in ASD.  Patients were categorized by CD4 levels prior to ART initiation as late (CD4 <200 or AIDS defining illness), generally recommended (CD4 >200 but <350), or early (CD4 350).  A categorical regression analysis using cumulative logits was used to determine if initiation of any ART across the categories differed by race, age, risk, and gender.  The model compares category 1 with 2 and 3 and categories 1 and 2 with 3.  Initial regimens were categorized as highly active antiretroviral therapy (HAART) as defined by current treatment guidelines, other triple (or more) therapy, dual ART, or other ART.

Results: Of the 4379 patients initiating ART, 27% were female, 49% were black, 39% were men who have sex with men (MSM), and 16% were injection drug users (IDUs).  Overall, 33% initiated ART early, 26% at generally recommended levels, and 40% initiated late.  Factors associated with increased odds of initiating at late relative to generally recommended or early and late or generally recommended compared with early were: Hispanic ethnicity (odds ratio [OR]=1.74, p<0.0001) and black race (OR=1.65, p<0.0001) compared with white race, and IDU (OR=1.48, p<0.0001) and heterosexual exposure (OR=1.29, p=0.02) compared with MSM.  Females (OR=0.55, p<0.0001) compared with males and persons aged <25 years (OR=0.53, p<0.0001) compared with persons aged >25 years were less likely to initiate late than at generally recommended or early, and less likely to initiate late or generally recommended compared with early.  The proportion of patients prescribed HAART as their initial regimen increased over the 5 year period.  More than half (58%) of the initial regimens were HAART, 27% dual ART, 9% other ART, and 6% other triple ART.

Conclusions: Differences by race/ethnicity and risk behavior were evidenced by late initiation of ART among Hispanics, blacks, IDUs and those heterosexually exposed.  The impact of when patients initiate ART on disease progression as well as initial regimen prescribed needs to be determined to continue to decrease morbidity and mortality among HIV-infected persons.