Background: No randomized comparisons exist between dolutegravir (DTG) and boosted-darunavir (DRV/b) for people initiating treatment with advanced HIV. Methods: Antiretroviral therapy (ART)-na & iuml;ve people with HIV (PWH) with CD4 < 200 cells/mm(3) or AIDS who started a first-line three-drug regimen with DTG or DRV/b were included. The primary outcome was a composite endpoint of newly diagnosed AIDS, serious non-AIDS events (SNAE), death, virological failure (VF), or discontinuation of the anchor drug due to failure or toxicity. A marginal structural Cox regression model was used to estimate the effect of starting DTG vs DRV/b-based regimens. Results: A total of 1323 advanced ART-na & iuml;ve PWH were included, 895 starting DTG and 428 DRV/b. The unweighted risks of the composite endpoint by 48 months were 21.1% (95% CI: 18.1; 24.1%) for DTG vs 37.9% (95% CI: 32.7; 43.2%) for DRV/b ( P < 0.001). First-line treatment with DTG showed a lower risk of experiencing the composite endpoint than DRV/b (wHR of DTG vs DRV/b 0.47, 95% CI: 0.35; 0.64, P < 0.001). Conclusion: Under the stated assumptions, this analysis indicates that in ART-na & iuml;ve PWH with advanced disease, ART initiation with DTG vs DRV/b-based regimens leads to a 50% reduction in the risk of AIDS/SNAE/death/VF/discontinuation. This observed difference is partly explained by discontinuation of the anchor drug. (c) 2025 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)