HIV viral load response to antiretroviral therapy according to the baseline CD4 cell count and viral load

Context It is unclear whether delay in initiation of antiretroviral therapy (ART) may lead to a poorer viral load response for patients with human immunodeficiency virus (HIV). Objective To characterize the relationship of viral load response to ART with baseline CD4 cell count and baseline viral load. Design Inception cohort of 3430 therapy-naive patients with HIV, of whom 3226 patients had at least 1 viral load count after the start of ART. Setting Three cohort studies of patients cared for in HIV clinics in Europe between 1996 and 2000. Patients All patients initiating ART consisting of at least 3 drugs initiated in or after 1996 and for whom CD4 cell count and viral load were available in the prior 6 months (at most). Main Outcome Measures Viral load decrease to below 500 copies/mL; viral load rebound to above 500 copies/mL (2 consecutive values). Results Of 3226 patients during the median follow-up of 119 weeks, 2741 (85%) experienced viral suppression to less than 500 copies/mL by 32 weeks. Relative hazards (RHs) of achieving this were 1.08 (95% confidence interval [CI], 0.98-1.21) and 0.94 (95% CI, 0.84-1.04) for baseline CD4 cell counts between 200 and 349 x 10(6)/L and baseline CD4 cell counts lower than 200 x 10(6)/L, respectively, compared with baseline CD4 cell counts of 350 x 10(6)/L or higher, after adjustment for several factors including baseline viral load. For baseline viral load, the RHs were 0.95 (95% CI, 0.84-1.07) and 0.65 (95% CI, 0.58-0.74), for 10000 to 99999 and 100000 copies/mL or greater, respectively, compared with less than 10000 copies/mL, but the probability of viral load lower than 500 copies/mL at week 32 was similar in all 3 groups. Subsequent rebound above 500 copies/mL was no more likely with a lower baseline CD4 cell count or higher viral load. Conclusion In this study, lower CD4 cell counts and higher viral loads at baseline were not associated with poorer virological outcome of ART. Those with baseline viral loads of greater than 100000 copies/mL had a slower rate of achieving viral suppression.