HIV diagnosis at CD4 count above 500 cells/mm3 and progression to below 350 cells/mm3 without antiretroviral therapy.

A trial to evaluate the risks and benefits of initiation of antiretroviral therapy (ART) in patients with high CD4 count (eg, > or =500 cells/mm3), in comparison with deferral (eg, to <350 cells/mm3), merits consideration. Two issues for consideration in designing such a trial are the proportion of patients seen in clinics who present with high CD4 count and the time it will take for those randomized to deferring ART to reach a level where ART must be initiated. Among 13,572 patients in the UK CHIC Study presenting since 1996, 3631 (27%) had a count > or =500 cells/mm3. Among 4268 ART-naive patients with at least one CD4 count in the 500 to 650 cells/mm3 range, the median time to <350 cells/mm3 (or start of ART) was 2.5 years, with a range of 2.1 to 3.1 years depending on the analysis approach. Viral load at baseline was a strong predictor of the time taken for the CD4 count to reach <350 cells/mm3, with the median ranging from 0.7 years in those with viral load > or =500,000 copies/mL to 4.7 years in those with <1000 copies/mL. This provides timely background data on ART-naive patients seen in clinical practice to support design of a trial to compare immediate with deferred ART in people with high CD4 count.