Background:
Efficiently improving transitions in care requires hospitals to target discharge interventions at those patients at high risk of potentially avoidable readmission (PAR). We previously derived the “HOSPITAL” score, an easy to use prediction model for medical patients (Table 1). This score had good discrimination for determining PARs in the hospital in which it was derived (C-statistic of 0.71). To assess its generalizability, we aimed to externally validate the “HOSPITAL” score in an international multicenter study.
Methods:
We applied the score to 124,212 adult patients consecutively discharged alive from the medical departments of 6 medical centers in the US, 1 in Israel, 1 in Canada, and 1 in Switzerland, between January and December, 2011. The outcome was any 30-day readmission that was classified as potentially avoidable using the previously validated SQLape algorithm. By comparing mainly ICD-9 codes from the two hospitalizations, SQLape excludes elective readmissions, foreseen readmissions such as chemotherapy, and readmissions for new diseases unknown during the preceding hospital stay unless a known complication of previously received treatment. The performance of the score was evaluated according to its discrimination (C-statistic, representing the area under the ROC curve) and its calibration (based on the Pearson goodness-of-fit statistic).
Results:
Among all patients in the cohort, the PAR rate was 9.5% (overall 30-day readmission rate was 14.5%). The discriminatory power of the “HOSPITAL” score to predict PAR was good with a C-statistic of 0.72 (95% CI 0.71-0.72). As in the derivation study, patients were classified into 3 risk categories: low (63%), intermediate (23%), and high risk (14%). The estimated proportions of PAR for each risk category matched exactly the observed proportion, with a consequent excellent calibration (p=0.97, with high p values indicating better fit; Table 2).
Conclusions:
The “HOSPITAL” score identified patients at high risk of 30-day potentially avoidable readmission with high discrimination when applied to a large international multicenter cohort of medical patients. The “HOSPITAL” score is the first score to focus on potentially avoidable (as opposed to all-cause) readmissions, using readily available predictors at the time of discharge, and that is externally validated in a large cohort in 4 different countries. This score has the potential to easily identify patients in need of more intensive transitional care interventions to prevent avoidable hospital readmissions.