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Background: Dual therapy (DT) with a ritonavir-boosted PI (PI/r) plus lamivudine has proven non-inferior (12% margin) to triple therapy (TT) with PI/r plus two nucleos(t)ide reverse transcriptase inhibitors [N(t)RTIs] in four clinical trials. It remains unclear whether DT is non-inferior based on the US FDA endpoint (virological failure with a margin of 4%) or in specific subgroups.Methods: We performed a systematic search (January 1990 to March 2017) of randomized controlled trials that compared switching of maintenance ART from TT to DT. The principal investigators were contacted and agreed to share study databases. The primary endpoint was non-inferiority of DT to TT based on the current FDA endpoint (4% non-inferiority margin for virological failure at week 48). We also analysed whether efficacy was modified by gender, active HCV infection and type of PI. Effect estimates and 95% CIs were calculated using generalized estimating equation-based models.Results: We found 881 references that yielded eight articles corresponding to four clinical trials (1051 patients). At week 48, 4% of patients on DT versus 3.04% on TT had experienced virological failure (difference 0.9%; 95% CI -1.2% to 3.1%), and 84.7% of patients on DT versus 83.2% on TT had <50 copies of HIV RNA/mL (FDA snapshot algorithm) (difference 1.4%; 95% CI -2.8% to 5.8%). Gender, active HCV infection and type of PI had no effect on differences in treatment efficacy between DT and TT.Conclusions: DT was non-inferior to TT using both current and past FDA endpoints. The efficacy of DT was not influenced by gender, active HCV infection status, or type of PI.