Being the first line of acute care, the emergency room (ER) plays an extremely important role in the overall healthcare system. According to guidelines established by the American College of Surgeons in 1962, typical emergency care services are designed to meet the needs of patients of every age group, and emphasize urgent care, screening, diagnostic testing, and simplified and rapid admission procedures [1]. Despite these services, there may be many limitations in the provision of emergency treatment and care for elderly patients. The knowledge of healthcare professionals and designs of the actual physical environment in ERs have not kept pace with special requirements of aging populations [2]. Thus, elderly patients with memory loss, limited mobility, and inadequate social support systems who arrive at an ER tend to encounter slow processing speeds and lower effectiveness of the ER's functioning system to address crises [1], [3].

The elderly visit the ER for a variety of reasons, which may be related to physical health, mental health, adverse drug reactions, social distancing, malnutrition, abuse, seasonal factors, and accidents [4], [5], [6]. Nearly 20% of elderly people in Finland were discharged due to a non-specific diagnosis, with common typical diagnoses including pneumonia (4.8%), general malaise and fatigue (4.3%), and heart failure (4.3%), and elderly patients with a nonspecific diagnosis tend to have higher medical costs than those of other patients [7]. Characteristics of emergency care treatments of elderly patients are usually not limited to a single symptom, meaning there are many complex hidden danger signals, including polypharmacy, multiple chronic diseases, and cognitive impairment. The risk of direct transfer from the ER to hospitalization of elderly patients was 2.5∼4.6-times higher than that of younger patients, and elderly patients were more likely to be admitted to intensive care units (ICUs). The hospitalization rate of the elderly increases with age, and the risk of direct hospitalization from the ER increases by 16% for every 10-year increase in age [8], [9]. The elderly may also experience more adverse health events, including disability, readmissions, or death during emergency treatment or after hospital discharge [10], [11], [12].

The acute-care model emphasizes an overall evaluation and care for the elderly. It is crucial to prevent and delay the occurrence of disabilities through early evaluations and interventions through the acute-care model [13], [14]. Therefore, screening of high-risk patients who are prone to adverse outcomes is one of the primary goals of emergency programs [14]. Guidelines of the American College of Emergency Physicians (ACEP) for elderly care in the ER recommend that screening tools used in the ER should be easy to apply, conform to the characteristics of the emergency environment, and effectively identify high-risk patients, in order to provide more resources for early interventions, thereby preventing the occurrence of adverse outcomes and functional declines [2], [15]. The Identification of Seniors at Risk (ISAR) screening tool has been translated and used in many countries and has shown appropriate psychometric properties [16], [17], [18]. However, currently there is no formally authorized Chinese translation of the ISAR scale, nor are there reliability and validity results for the Chinese scale. Therefore, the main purpose of this study was to establish the reliability and validity testing of a traditional Chinese version of the ISAR screening tool to determine whether this tool is suitable for clinical application in Taiwan's ERs to identify elderly patients who are prone to adverse outcomes, including an ER revisit within 72 h, an ER revisit within 1 month, hospital admission within 1 month, and mortality within 1 month after discharge from the ER. We also further explored related factors.