Cardiovascular Hospitalizations Among Older Adults in the US and Denmark

IMPORTANCE Cardiovascular disease is the leading cause of death in the US. However, it remains unclear how the burden of cardiovascular events in the US compares with that of other high-income countries with distinct health care systems like Denmark, both overall and by income. OBJECTIVE To compare cardiovascular hospitalization rates (acute myocardial infarction [MI], heart failure [HF], ischemic stroke) and associated outcomes among adults 65 years or older, overall and by income, between the US and Denmark. DESIGN, SETTING, AND PARTICIPANTS This population-based cross-sectional study used national data from the US and Denmark from January 1, 2021, to January 1, 2022. The study population included all Medicare beneficiaries 65 years or older in the US and all adults 65 years or older in Denmark. MAIN OUTCOMES AND MEASURES The primary outcome was age- and sex-standardized hospitalization rates for MI, HF, and ischemic stroke, as well as 30-day all-cause mortality rates. RESULTS The US study population included 58 614 110 adults 65 years or older (mean [SE] age, 74.6 [7.7] years; 32 179 146 female [54.9%]) of whom 1 171 058 (2.0%) were hospitalized for a cardiovascular event. The Danish study population included 1 176 542 adults 65 years or older (mean [SE] age, 75.3 [7.1] years; 634 217 female [53.9%]) of whom 16 305 (1.4%) were hospitalized with a cardiovascular event. The overall age- and sex-standardized cardiovascular hospitalization rate was significantly higher in the US compared with Denmark (risk ratio [RR], 1.50; 95% CI, 1.47-1.52), as were associated 30-day all-cause mortality rates (RR, 1.12; 95% CI, 1.06-1.17). Across conditions, the risk of hospitalization for MI (RR, 1.56; 95% CI, 1.51-1.61) and HF (RR, 2.37; 95% CI, 2.31-2.43) was significantly higher in the US compared with Denmark, whereas hospitalizations for ischemic stroke were lower (RR, 0.90; 95% CI, 0.88-0.93). Overall cardiovascular hospitalization rates in the US were more than 2-fold higher among low-income adults compared with higher-income adults (RR, 2.38; 95% CI, 2.25-2.47), whereas the magnitude of income-based disparities was smaller in Denmark (RR, 1.45; 95% CI, 1.39-1.50). CONCLUSIONS AND RELEVANCE In this international cross-sectional study, cardiovascular hospitalization rates were significantly higher in the US compared with Denmark. There were income-based differences in the burden of cardiovascular hospitalizations in both countries, although the magnitude of these disparities was much greater in the US.