Temporal trends in infection-related hospitalizations among patients with heart failure: A Danish nationwide study from 1997 to 2017

Background: Despite improved survival, hospitalization is still common among patients with heart failure (HF). Objective: This study aimed to examine temporal trends in infection-related hospitalization among HF patients and compare it to temporal trends in the risk of HF hospitalization and death. Methods: Using Danish nationwide registers, we included all patients aged 18 to 100 years, with HF diagnosed between January 1, 1997 and December 31, 2017, resulting in a total population of 147.737 patients. The outcomes of interest were primarily infection-related hospitalization and HF hospitalization and secondarily all-cause mortality. The Aalen Johansen's estimator was used to estimate 5-year absolute risks for the primary outcomes. Additionally, cox analysis was used for adjusted analyses. Results: The population had a median age of 74 [64, 82] years and 57.6 % were males. Patients with HF had a higher risk of infection over time 16.4 % (95% CI 16.0-16.8) in 1997 to 2001 vs 24.5% (95% CI 24.0-24.9) in 2012 to 2017. In contrast, they had a lower risk of HF hospitalization 26.5% (95% CI 26.1-27.0) in 1997 to 2001 vs 23.2% (95% CI 22.8-23.7) in 2012 to 2017. The risk of infection stratified by infection type showed similar trends for all infection types and marked the risk of pneumonia infection as the most significant in all subintervals. Conclusion: In the period from 1997 to 2017, we observed patients with HF had an increased risk of infection-related hospitalization, driven by pneumonia infections. In contrast, the risk of HF hospitalization decreased over time.