Pain at Discharge as the Strongest Predictor of Early Readmission Risk Among Multiple Key In-hospital Timepoints in Internal Medicine

BACKGROUND: Hospital readmissions are a key metric of healthcare quality and cost. Pain has been implicated as a predictor of readmissions, yet its role in internal medicine remains underexplored. OBJECTIVE: To investigate the association between in-hospital pain assessment at different timepoints and subsequent hospital readmissions in internal medicine patients. DESIGN: Retrospective cross-sequential cohort study. PARTICIPANTS: 7277 patients admitted to the Internal Medicine Department of a Swiss network of public hospitals from 2020 to 2023. MEASURES: Pain intensity was assessed using the Visual Analogue Scale (VAS) at admission, during hospitalisation, and at discharge. Admissions and readmissions were analysed as all-cause hospitalisations, because only the main diagnosis is routinely recorded, which may not accurately reflect pain-related causes. Severity-related factors such as cost weight and hospital length of stay were included as covariates to control for case-mix differences. Multivariate logistic regression models were used to examine predictors of readmission at 18 and 30 days, and 3, 6, and 9 months post-discharge. KEY RESULTS: The mean VAS score significantly decreased from 4.7 at admission to 1.9 at discharge. Readmission rates were 1.1% at 18 days, 10% at 3 months, 14.4% at 6 months, and 17.8% at 9 months. Pain at admission, peak pain during hospitalisation, and pain at discharge were each associated with increased readmission risk, though with different temporal patterns. Pain at discharge (VAS) was an independent predictor of readmissions, with odds ratios of 1.10 (95% CI:1.01-1.19) at 30 days, 1.06 (95% CI: 1.01-1.13) at 3 months and 1.05 (95% CI: 1.00-1.10) at 6 months. Subgroup analysisshowed that pain at discharge was associated with a 31% increase in the risk of 18-day readmission among older adults (≥65 years) and a 26% increase in the risk of 30-day unplanned readmission among younger patients (≤65 years). CONCLUSIONS: Although all three timepoints provide prognostic value, pain at discharge is a significant predictor of readmissions, emphasising the need for comprehensive pain management during hospitalisation and discharge planning. Targeted interventions for high-risk groups may improve outcomes and reduce healthcare utilisation.