Multimorbidity patterns in adults admitted to hospital with heart failure: an analysis of 175 million hospitalisation episodes

Abstract Background The prevalence of heart failure (HF) is increasing as a result of population ageing, improved survival following myocardial infarction and the widespread uptake of evidence-based HF treatments. Greater understanding of multimorbidity patterns in patients with HF may enable the development of treatment strategies that target multiple, related long-term conditions (LTCs), producing synergistic benefits. Purpose To characterise multimorbidity patterns in patients with HF and compare these to a matched population without HF. Methods A retrospective matched cohort study was conducted using the United States National Readmission Database (NRD), 2010–2020. International Classification of Disease (ICD) codes were used to identify HF and 92 other common LTCs. The most frequent combinations of LTCs were identified for individuals with HF and a control cohort of individuals of the same age and sex, with a non-HF-related hospital admission in the same year (matched in a 1:5 ratio). Multivariable regression analysis (adjusted for age, sex, socioeconomic status, tobacco use, year of hospitalisation, and hospital characteristics) was used to evaluate the association between multimorbidity burden, length of stay (LOS; negative binomial regression) and 30-day readmission (logistic regression). Results From a total of 175,388,410 hospitalisation episodes, 3,913,924 individuals with an HF-related hospitalisation were identified and matched to 19,552,954 controls (Figure 1a). The median (interquartile range, IQR) age of a patient admitted with HF was 74 (63–85) years; 1,856,268 (47.5%) were female. The most common comorbidities in those with HF were hypertension (87.2 vs. 72.8% in matched controls), chronic kidney disease (CKD; 55.3 vs. 34.6%), coronary artery disease (CAD; 53.7 vs. 31.0%), dyslipidaemia (46.9 vs. 39.7%), diabetes (46.6 vs. 33.9%), atrial fibrillation (AF; 43.0 vs. 23.0%) and anaemia (33.2 vs. 30.1%; p all < 0.001). Patients with HF had a greater number of LTCs compared with matched controls (median [IQR] 7 [5–9] vs. 6 [4–8]; p < 0.001). From 2010–2020, the number of LTCs in those with an HF admission increased (from 6 [4–8] in 2020, to 8 [6–10] in 2020; Figure 1b). The most common multimorbidity patterns in those with HF are presented in Figure 2. In the HF cohort, a greater multimorbidity burden was associated with a longer LOS (+6% for each additional LTC; 95% confidence interval [CI] 5–7%; p<0.001) and greater risk of 30-day readmission (adjusted odds ratio [aOR] for 6 vs. 0 LTCs: 1.15, 95% CI 1.08–1.22; aOR for ≥12 vs. 0 LTCs: 1.54, 95% CI 1.45–1.64). Conclusions Patients admitted to hospital with HF have a significant burden of multimorbidity, which has increased over time and is associated with increased length of stay and unplanned hospital re-admission. The high prevalence of multiple LTCs warrants the development of novel treatment strategies that target common multimorbidity patterns observed in HF.