Diverging trends in total and heart failure-specific disease burden by age: A 20-year nationwide study in Denmark

Background Despite improvements in the prognosis of heart failure (HF), recurrent hospitalisations remain an understudied and substantial disease burden. Whether trends in total and HF-specific hospitalisations differ by age remains unknown. Purpose To examine age-specific trends in total and HF-specific hospitalisation rates. We hypothesized that both HF-specific and total disease burden have declined for all age groups in a period focusing on the implementation of guideline-directed therapies. Methods Using Danish nationwide registries, we identified all patients with incident HF during two calendar periods (1998-2002 (reference) and 2018-2022). Patients were categorised into three age groups (<65 years, 65-79 years, and ≥80 years) according to age at HF diagnosis. All patients were followed for up to 5 years. Temporal changes in total and HF-specific hospitalisation rates were examined using the multivariable proportional rates model of Lin, Wei, Yang, and Ying1 to account for recurrent events, adjusting for sex and relevant comorbidities (diabetes, atrial fibrillation, ischemic heart disease, cancer, stroke, hypertension, and chronic obstructive pulmonary disease). All-cause mortality was assessed using Kaplan–Meier estimates and multivariable Cox regression, adjusted for the same covariates. Results A total of 82,382 patients were included: 40,050 from 1998-2002: (mean age 74.3 years; 19% <65 years, 40% 65-79, and 41% ≥80) and 42,332 from 2018-2022 (mean age 72.5 years; 24% <65 years, 40% 65-79, and 36% ≥80). HF-specific hospitalisation rates declined from 12.1 to 8.2 per 100 person-years (rate ratio (RR) 0.56, 95% CI 0.54-0.59, p<0.001), with reductions observed in all age groups. The largest relative reduction was seen in patients aged <65 (9.3 to 5.2; RR 0.47, 0.42-0.53), followed by those aged 65–79 years (11.7 to 7.8; RR 0.51, 0.48-0.54), and those ≥80 years (15.1 to 12.8; RR 0.71, 0.67-0.76; all p<0.001). Conversely, total hospitalisation rates rose from 49.9 to 64.6 per 100 person-years (RR 1.18, 1.15-1.20, p<0.001) overall, and consistently across age groups (RR 1.41, 1.22, 1.20 for ages <65 years, 65-79 years, and ≥80 years; all p<0.001). Five-year all-cause mortality declined from 60.9% to 43.8% overall (hazard ratio (HR) 0.58, 95% CI 0.57-0.59, p<0.001), with significant reductions in all age groups (<65 years: HR 0.45, 0.42-0.49; 65-79 years: HR 0.52, 0.51-0.55; ≥80 years: HR 0.73, 0.71-0.75; all p<0.001). Conclusion Over 20 years, HF hospitalisation rates have declined substantially across all ages, with the greatest reduction in patients aged <65 years and the smallest in those aged ≥80 years. In contrast, total hospitalisation rates have increased, likely reflecting improved survival, prolonged exposure to multimorbidity, and changing patterns of healthcare use. This diverging trend should be considered in the future organization of HF care to address the growing burden of non-HF hospitalisationsHospitalisation RRs: 1998–2002 vs 2018–2022