Post-Emergency Geriatric Units (PEGUs) aim to reduce hospital length of stay (LOS) and prevent functional decline by facilitating earlier discharge.

This study aim to identify factors linked to prolonged hospitalization to improve patient selection for PEGU.

In this retrospective study at the University Hospital of Angers (Dec 2022–Feb 2024), 590 eligible PEGU patients were analyzed. LOS was categorized as short (0–5 days) or prolonged (6 or more days). Sociodemographic, clinical, and biological data were assessed using univariate and multivariate logistic regression.

Median age was 88, 62.2% were female, and 69% lived at home; 42% had prolonged LOS. Prolonged stay was associated in univariate analysis with higher Charlson Comorbidity Index (OR: 1.10 [1.02−1.19], p = 0.015 ), elevated CRP  >  64 mg/L (2.07 [1.46−2.92], p < 0.001 ), and higher Clinical Frailty Scale (1.79 [1.23−2.59], p = 0.002) . The multivariate analysis showed that a CRP levels ≥64 mg/L (OR 1.92 [1.35−2.75], p  <  0.001) and a CFS equal to or superior to 7 (OR 1.59 [1.07−2.36], p = 0.022) were associated with prolonged LOS.

Frailty and inflammation independently predict longer stays. Limitations include retrospective design and patient exclusions.

Frailty and elevated CRP are key predictors of prolonged PEGU stay. Although causality cannot be established due to the retrospective design and potential biases, these findings may help to better characterize older patients who could potentially benefit from PEGU interventions