Meta-analysis of two randomized controlled trials comparing combined zidovudine and didanosine therapy with combined zidovudine, didanosine, and nevirapine therapy in patients with HIV. INCAS study team.

Author(s): Raboud JM, Rae S, Vella S, Harrigan PR, Bucciardini R, Fragola V, Ricciardulli D, Montaner JS

Affiliation(s): Department of Health Care and Epidemiology, University of British Columbia, Vancouver, Canada. jraboud@hivnet.ubc.ca

Publication date & source: 1999-11-01, J Acquir Immune Defic Syndr., 22(3):260-6.

Publication type: Clinical Trial; Meta-Analysis; Randomized Controlled Trial

OBJECTIVES: To extend the range of CD4 counts in which a plasma viral load nadir (pVL) <20 copies/ml was known to be predictive of the duration of virologic response. To determine whether baseline pVL is predictive of virologic response during the study periods. METHODS: A meta-analysis was conducted of the original individual patient data from two randomized controlled trials comparing zidovudine (ZDV)/didanosine (ddI) with ZDV/ddI/nevirapine (NVP). RESULTS: In total, 87 patients received ZDV/ddI and 83 received ZDV/ddI/NVP. Study subjects on triple therapy with baseline pVL <100,000 copies/ml were more likely to achieve a pVL <400 copies/ml (odds ratio [OR] = 2.49; p = .02) and <20 copies/ml (OR = 4.76; p = .001) during the trial than those with baseline pVL > 100,000 copies/ml. Among triple therapy patients, the relative risk of virologic failure was higher for patients with higher baseline pVL (rate ratio [RR] = 2.51/log10 copies/ ml; p = .01), after controlling for compliance and pVL nadir. The relative risks of virologic failure associated with pVL nadir <20 copies/ml and between 21 and 400 copies/ml were .04 (p = .0001) and .56 (p = .26), respectively, compared with patients with a pVL nadir >400 copies/ml. CONCLUSIONS: We have extended our earlier results that achieving a pVL nadir <20 copies/ml is important for maintaining virologic suppression. In particular, we have demonstrated that a pVL nadir <20 copies/ml is at least fivefold more protective against virologic failure than achieving a pVL nadir between 20 and 400 copies/ml. Baseline pVL is significantly associated with the probability of achieving and sustaining virologic suppression.