Long-term morbidity and mortality of COVID-19 in patients receiving maintenance dialysis: a multi-center population-based cohort study

Background — Many questions remain about the maintenance dialysis population who survived COVID-19. Previous literature has focused on outcomes associated with the initial SARS-CoV-2 infection but it may underestimate the impact of disease. This study describes the long-term morbidity and mortality among patients receiving maintenance dialysis in Ontario, Canada who survived their SARS-CoV-2 infection, and the risk factors associated with long-term mortality.

Methods — We conducted a population-based cohort study of patients receiving maintenance dialysis in Ontario, Canada who tested positive for SARS-CoV-2 and survived 30 days between March 14, 2020 and December 1, 2021 (pre-Omicron), with follow-up until September 30, 2022. Our primary outcome was all-cause mortality, while our secondary outcomes included reinfection, composite of cardiovascular (CV)-related death or hospitalization, all-cause hospitalization, and admission to long-term care or complex continuing care. We also examined risk factors associated with long-term mortality using multivariable Cox proportional hazards regression.

Results — We included 798 COVID-19 survivors receiving maintenance dialysis. After the first 30 days of infection, death occurred at a rate of 15.0 per 100 person-years (95% CI 12.9 – 17.5) over a median follow-up of 1.4 years (IQR 1.1, 1.7) with a nadir of death at approximately 0.5 years. Reinfection, composite CV death or hospitalization, and all-cause hospitalization occurred at a rate (95% CI) of 15.9 (13.6 – 18.50), 17.4 (14.9 – 20.4), and 73.1 (66.6 – 80.2) per 100 person-years, respectively. In addition to traditional predictors of mortality, ICU admission for COVID-19 had a prolonged impact on survival (adjusted hazard ratio [HR] 2.6, 95% CI 1.6 – 4.3). Reinfection with SARS-CoV-2 among 30-day survivors increased all-cause mortality (adjusted HR 2.2, 95% CI 1.4 – 3.3).

Conclusions — The burden of COVID-19 persists beyond the period of acute infection in the maintenance dialysis population in Ontario with high rates of death, reinfection, all-cause hospitalization, and CV disease among COVID-19 survivors.