BACKGROUND: Mortality among people with HIV declined with the introduction of combination antiretroviral therapy. We investigated trends over time in all-cause and cause-specific mortality in people with HIV from 1999-2020.

METHODS: Data were collected from the D:A:D cohort from 1999 through January 2015 and RESPOND from October 2017 through 2020. Age-standardized all-cause and cause-specific mortality rates, classified using Coding Causes of Death in HIV (CoDe), were calculated. Poisson regression models were used to assess mortality trends over time.

RESULTS: Among 55716 participants followed for a median of 6 years (IQR 3-11), 5263 participants died (crude mortality rate [MR] 13.7/1000 PYFU; 95%CI 13.4-14.1). Changing patterns of mortality were observed with AIDS as the most common cause of death between 1999- 2009 (n = 952, MR 4.2/1000 PYFU; 95%CI 4.0-4.5) and non-AIDS defining malignancy (NADM) from 2010 -2020 (n = 444, MR 2.8/1000 PYFU; 95%CI 2.5-3.1). In multivariable analysis, all-cause mortality declined over time (adjusted mortality rate ratio [aMRR] 0.97 per year; 95%CI 0.96, 0.98), mostly from 1999 through 2010 (aMRR 0.96 per year; 95%CI 0.95-0.97), and with no decline shown from 2011 through 2020 (aMRR 1·00 per year; 95%CI 0·96-1·05). Mortality due all known causes except NADM also declined over the entire follow-up period.

CONCLUSION: Mortality among people with HIV in the D:A:D and/or RESPOND cohorts decreased between 1999 and 2009 and was stable over the period from 2010 through 2020. The decline in mortality rates was not fully explained by improvements in immunologic-virologic status or other risk factors.