Accuracy of the Simplified HOSPITAL Score to Predict Nonelective Readmission in a Brazilian Tertiary Care Public Teaching Hospital

BACKGROUND AND OBJECTIVES: Predictive models to identify patients at high risk of readmission have gained the attention of health care teams, which have focused the strategies to reduce unnecessary readmissions on the "at-risk" patients. The HOSPITAL score includes 7 predictor variables with a C-statistic of 0.70 or more when applied to international datasets. Its simplified version retains a C-statistic at around the same level, but only incipient external validation has been attempted to date. The primary objective of this study was to evaluate the prognostic accuracy of the simplified HOSPITAL score to predict nonelective hospital readmissions in a tertiary care public teaching hospital in Brazil. METHODS: We used a retrospective cohort that included all patients discharged from the internal medicine service of a Brazilian tertiary care public teaching hospital in 2018. We excluded patients who died before index discharge, were transferred to another institution, left against medical advice, or were readmitted electively. We calculated the simplified HOSPITAL score for each admission, and admissions were divided into low (0-4 points) or high risk (≥ 5 points) of nonelective 30-day readmission. We estimated accuracy, area under the receiver operating characteristic curve (AUC), and observed/expected (O/E) readmission ratio; the latter using the mid-P exact test with Miettinen's modification at a 95% confidence interval (CI). A P value < .05 was considered significant. RESULTS: A total of 4472 hospital discharges were analyzed during the study period after application of the exclusion criteria. The nonelective 30-day readmission rate was 14.0% (n = 625). Of all patients discharged, 3173 (71.0%) were considered to be at low risk and 1299 (29.0%) at high risk of readmission according to the simplified HOSPITAL score. The AUC was 0.68 (95% CI: 0.66-0.71; P < .001). The nonelective 30-day readmission rate was 9.2% in the low-risk group (expected: 9.2%; O/E: 1.0 [95% CI: 0.89-1.12]) and 25.7% in the high-risk group (expected: 27.2%; O/E: 0.95 [95% CI: 0.85-1.05]) ( P < .001). At a cut-off of 5 points, the score had a sensitivity of 53.4%, specificity of 74.9%, positive predictive value of 25.7%, and negative predictive value (NPV) of 90.8%. CONCLUSIONS: The parameters of the score were almost identical to the original study, with better applicability to exclude low-risk patients given its high NPV. Additional adjustments are still needed for better applicability in daily clinical practice.