Development and validation of a prediction model for 1-year all-cause rehospitalisation after discharge in patients with heart failure with preserved ejection fraction based on the systemic immune-inflammation index

Objective To develop and internally validate a practical model for predicting the risk of at least one all-cause rehospitalisation within 1 year after discharge in patients with heart failure with preserved ejection fraction (HFpEF), with particular attention to the systemic immune-inflammation index (SII). Methods This single-center observational study was based on retrospective analysis of index-admission data and follow-up records from patients with HFpEF treated at Fuyang People's Hospital between January 2022 and January 2024. Among 341 initially eligible patients, 29 were lost to follow-up, leaving a final analytic cohort of 312 patients. The cohort was divided into a training set ( n = 218) and a validation set ( n = 94) using outcome-stratified random sampling. The primary endpoint was the occurrence of at least one all-cause rehospitalisation within 1 year after discharge. Candidate predictors were screened by least absolute shrinkage and selection operator logistic regression in the training set, followed by multivariable logistic regression to construct the final model and nomogram. Model performance was assessed by discrimination, calibration, and decision curve analysis. Results LnSII, LnNT-proBNP, LnLp(a), GFR, and hypertension remained in the final model. The model showed good discrimination, with an area under the receiver operating characteristic curve of 0.8468 in the training set and 0.8302 in the validation set. At the optimal cutoff derived from the training set, sensitivity and specificity were 0.7101 and 0.8993 in the training set and 0.5333 and 0.8750 in the validation set, respectively. Calibration was acceptable in both cohorts according to the Hosmer–Lemeshow test, and decision curve analysis suggested potential clinical utility. Conclusion A 5-variable model incorporating LnSII, LnNT-proBNP, LnLp(a), GFR, and hypertension showed good discrimination, acceptable calibration, and potential clinical usefulness for predicting 1-year all-cause rehospitalisation after discharge in patients with HFpEF. External validation is needed before broader application.