Comparative prognostic performance of identification of seniors at risk tool and national early warning score for 30-day adverse outcomes in older emergency department patients

Older adults account for an increasing proportion of emergency department (ED) visits and experience disproportionately high rates of short-term adverse outcomes. Accurate early risk stratification is therefore essential to guide monitoring, disposition, and resource allocation. Physiology-based early warning scores and geriatric risk-screening tools represent distinct approaches to prognostication, yet their comparative performance in older ED populations remains insufficiently defined. This study aimed to directly compare the prognostic accuracy of the Identification of Seniors at Risk (ISAR) questionnaire and the National Early Warning Score (NEWS) for predicting 30-day adverse outcomes in older adults presenting to the ED. This prospective observational cohort study was conducted in a tertiary-care emergency department between January and March 2021. Consecutive patients aged ≥ 65 years were enrolled, with only index visits included. ISAR and NEWS were calculated at ED presentation according to standard definitions. The primary endpoint was a 30-day composite adverse outcome comprising unplanned ED revisits, hospital admission, intensive care unit admission, or all-cause mortality. Receiver operating characteristic (ROC) analyses were performed to assess discriminative performance, with areas under the curve (AUCs) compared using the DeLong test. Binary logistic regression models were used to estimate associations between predefined score thresholds (ISAR ≥ 2; NEWS ≥ 5) and outcomes, reported as odds ratios (ORs) with 95% confidence intervals. A total of 498 patients were included, with 48% experiencing at least one component of the composite outcome within 30 days. ISAR demonstrated superior discrimination for the composite endpoint compared with NEWS (AUC 0.747 vs. 0.650; DeLong p < 0.001) and was more accurate for predicting ED readmission, while NEWS demonstrated a higher point estimate for mortality prediction (AUC 0.869 vs. 0.792, DeLong p = 0.058). In logistic regression analyses, ISAR ≥ 2 was associated with a 5.85-fold increase in odds of adverse outcomes, whereas NEWS ≥ 5 conferred a 3.61-fold increase. In older adults presenting to the ED, ISAR and NEWS capture different dimensions of risk and demonstrate distinct prognostic strengths. ISAR more effectively identifies broader vulnerability associated with composite adverse outcomes, while NEWS is superior for short-term mortality prediction. These findings highlight the importance of aligning risk stratification tools with the specific outcomes of interest in geriatric emergency care.