Early Versus Later 30-Day Readmissions in Older Adults: Signals of Unresolved Illness Rather Than Frailty

Background

Thirty-day readmissions in older adults are commonly attributed to frailty and multimorbidity. However, early readmissions may reflect unresolved acute illness or deficiencies in transitional care rather than baseline vulnerability. Distinguishing early from later readmissions may help identify modifiable system-level factors. Thus, we aimed to determine predictors of early (<7-day) versus later (7–30-day) 30-day readmissions in general medical patients.

Methods

We conducted a retrospective cohort study of adult general medical inpatients admitted between January–June 2023 and January–June 2024 in a tertiary hospital. Patients readmitted within 30 days were included and categorised as early (<7 days) or later (7–30 days). Demographic, frailty (Rockwood Clinical Frailty Score), index admission, and discharge variables were analysed using univariable methods and multivariable logistic regression.

Results

Of 3,682 admissions, 263 (7.1%) resulted in 30-day readmission, including 79 (30.0%) early readmissions. Patients with early readmission were slightly younger than those with later readmission (mean 67.2 vs 70.0 years, p=0.224), although this difference was not statistically significant. Overall, baseline characteristics, including age, sex, frailty, and comorbidity burden, were not associated with timing of readmission. Early readmissions were more likely to follow hospital-acquired pneumonia (16.5% vs 6.0%, p=0.007) and were less frequently discharged home (78.5% vs 89.7%, p=0.015). Early readmissions were more commonly related to the index admission (70.9% vs 56.0%, p=0.023). In multivariable analysis, hospital-acquired pneumonia (OR 2.93, p=0.017) and discharge non-home (OR 2.79, p=0.011) independently predicted early readmission, while age was not independently associated.

Conclusion

Among patients readmitted within 30 days, early readmissions are driven by index admission complications and discharge context rather than age, frailty, or baseline characteristics. These findings suggest early readmissions represent unresolved acute illness and transitional care gaps, highlighting targets for intervention including complication prevention, discharge optimisation, and enhanced early post-discharge support.