External validation of the "simplified hospital" scale as a predictor of 30-day readmission after hospitalisation in osi araba medical services.

Background: A readmission is defined as a new admission to hospital for at least one night in the 30 days following a discharge. Some are caused by events unrelated to the reason for the initial admission (unavoidable) and others caused by the same pathology (related). Different predictive models allow the identification of patients at higher risk of readmission. The "HOSPITAL simplified" score stands out for its performance and simplicity.

Aim: To validate the "HOSPITAL simplified" scale in a cohort of patients at the University Hospital of Alava.

Method: Review of patients discharged from OSI Araba Medical Services in June and November 2023. The scale was applied to each of them and re-admission was studied in the 30 days following discharge. The Brier Score, discrimination and calibration capacity were analysed, using the guidelines of the TRIPOD declaration.

Results: In 1849 discharges there were 240 unscheduled readmissions: 73 for causes unrelated to the previous admission and 151 related. For predicting related readmissions the scale obtained a Brier score = 0.0703. The mean score for cases with related readmission was 4.7 versus 2.66 for cases without readmission (P < 0.001). The area under the ROC curve = 0.747. Related readmission occurred in 29.3% of patients at high risk, compared to 17.3% predicted by the scale.

Conclusions: The "HOSPITAL simplified" scale showed in OSI Araba a higher discrimination capacity than the original series although it underestimated the real risk. The scale offers good portability.