In Europe, tax-based healthcare systems (THS) and social health insurance systems (SHI) coexist. We examined differences in 30-day mortality among critically ill patients aged ≥ 70 years treated in intensive care units in a THS or SHI. Retrospective cohort study. 2406 (THS n = 886; SHI n = 1520) critically ill ≥ 70 years patients in 129 ICUs. Generalized estimation equations with robust standard errors were chosen to create population average adjusted odds ratios (aOR). Data were adjusted for patient-specific variables, organ support and health economic data. The primary outcome was 30-day-mortality. Numerical differences between SHI and THS in SOFA scores (6 ± 3 vs. 5 ± 3;
p= 0.002) were observed, but clinical frailty scores were similar (> 4; 17% vs. 14%; p= 0.09). Higher rates of renal replacement therapy (18% vs. 11%; p< 0.001) were found in SHI (aOR 0.61 95%CI 0.40–0.92; p= 0.02). No differences regarding intubation rates (68% vs. 70%; p= 0.33), vasopressor use (67% vs. 67%; p= 0.90) and 30-day-mortality rates (47% vs. 50%; p= 0.16) were found. Mortality remained similar between both systems after multivariable adjustment and sensitivity analyses. The retrospective character of this study. Baseline risk and mortality rates were similar between SHI and THS. The type of health care system does not appear to have played a role in the intensive care treatment of critically ill patients ≥ 70 years with COVID-19 in Europe.