Clinical Progression Rates by CD4 Cell Category Before and After the Initiation of Combination Antiretroviral Therapy (cART)

OBJECTIVE: Rates of AIDS defining event (ADE), serious ADE and death by CD4 and HIV RNA categories before and after combination antiretroviral therapy (cART) initiation are lacking for high CD4 counts. METHODS: Event rates were estimated within CD4 cell strata using a Poisson regression model adjusting for sex, exposure category, age, and current HIV RNA (<4, 4-4.99, ≥5 log copies/ml), and including an interaction term between the CD4 cell count and cART indicator. RESULTS: 7317 and 6376 persons contributed to "naïve " and "cART " groups respectively, of whom 3911 contributed to both. At the same CD4 level, the risk of ADE was nearly 2 fold higher during naive follow-up compared to cART for CD4 <500 cells/mm(3). However, after adjustment for current HIV RNA, the risk of ADE became similar for both groups except for CD4 count <200 cells/mm(3) when it is 35% (6-72%) higher for naives. The same results were observed for the risk of serious ADE. There was no evidence of a difference in risk of death between naive and cART follow-up at specific CD4 categories even after adjustment for HIV RNA. CONCLUSION: Within CD4 cell strata above 200 cells/mm(3), the risk of ADE before ART initiation is higher than it is following cART initiation.