To assess the evidence for the effectiveness of increasing numbers of drugs in antiretroviral combination therapy.
Systematic review, meta-analysis, and meta-regression of fully reported randomised controlled trials. All studies included compared quadruple versus triple therapy, triple versus double therapy, double versus monotherapy, or monotherapy versus placebo or no treatment.
Patients with any stage of HIV infection who had not received antiretroviral therapy.
Main outcome measures
Changes in disease progression or death (clinical outcomes); CD4 count and plasma viral load (surrogate markers).
Six electronic databases, including Medline, Embase, and the Cochrane Library, searched up to February 2001.
54 randomised controlled trials, most of good quality, with 66 comparison groups were included in the analysis. For both the clinical outcomes and surrogate markers, combinations with up to and including three (triple therapy) were progressively and significantly more effective. The odds ratio for disease progression or death for triple therapy compared with double therapy was 0.6 (95% confidence interval 0.5 to 0.8). Heterogeneity in effect sizes was present in many outcomes but was largely related to the drugs used and trial quality.
Evidence from randomised controlled trials supports the use of triple therapy. Research is needed on the effectiveness of quadruple therapies and the relative effectiveness of specific combinations of drugs.
What is already known on this topicTriple combination antiretroviral therapy is accepted by clinicians and patients as the usual treatment for HIV and has evolved through an incremental strategy in the numbers of drugs combinedGuidance on treatment, however, has predominantly been based on early reports of researchThere are no published analyses that assess the effectiveness of the increasing numbers of drugs used in combinationWhat this study addsThe results of this systematic review support the use of triple therapy but there is inadequate evidence for quadruple or higher combinationsHeterogeneity in the effect estimates seems to result from variable effectiveness of different drug combinations, trial duration, and problems with study quality