Different waist circumference-based definitions of obesity and hospital length of stay in heart failure

Abstract Background Central obesity is a modifiable cardiovascular risk factor and a key focus of preventive cardiology. Waist circumference (WC) is widely used to define abdominal obesity, yet various thresholds are applied, which may influence risk classification and clinical interpretation in heart failure (HF). Purpose To evaluate whether two WC-based definitions of central obesity differ in their predictive value for hospital length of stay (LOS) in older adults with HF. Methods This prospective study included 250 patients aged ≥ 60 years hospitalised for decompensated chronic HF. Anthropometric measurements were obtained after clinical stabilisation and before discharge. Two WC thresholds were analysed: Definition 1: ≥ 94 cm (men) / ≥ 80 cm (women); Definition 2: ≥ 102 cm (men) / ≥ 88 cm (women). LOS was analysed using negative-binomial regression including demographic, clinical, laboratory, nutritional, and frailty-related variables. The following factors were considered as potential determinants of hospital length of stay: age, sex, NYHA class, NT-proBNP, haemoglobin, renal function, C-reactive protein, presence of hypertension, diabetes, coronary artery disease, atrial fibrillation, nutritional status, and frailty indicators. Results In baseline comparisons, mean LOS did not differ significantly between patients with and without central obesity according to Definition 1 (p = 0.056). When using Definition 2, patients with central obesity had a significantly longer LOS (p 0.05). In multivariable models: • Definition 1: independent predictors of longer LOS were NYHA IV (IRR 1.223, 95 % CI 1.034–1.446; p = 0.019) and NT-proBNP (IRR 1.003 per 100 pg/mL, 95 % CI 1.002–1.004; p 0.001). • Definition 2: independent predictors were haemoglobin (IRR 0.923, 95 % CI 0.860–0.992; p = 0.029) and NT-proBNP (IRR 1.004 per 100 pg/mL, 95 % CI 1.002–1.006; p 0.001). For both definitions, WC-based obesity categories were not independently associated with LOS, and varying thresholds did not alter model performance or the set of significant predictors. Conclusions Neither of the WC-based definitions of central obesity independently predicted hospital length of stay in older adults with HF. The difference observed for the higher cut-off in baseline comparisons likely reflects the impact of disease burden and metabolic status rather than adiposity itself. Nevertheless, supporting individuals in maintaining a healthy body weight and waist profile remains essential for both primary and secondary prevention of HF and other cardiovascular diseases.