Several factors enhance the risk of ED visits and hospital readmissions, including old age, lower income, multiple chronic conditions, e.g., COPD, and previous history of frequent hospitalizations. Living alone or requiring home care services increases the likelihood of hospital readmission among older adults [1,2]. Additionally, many patients discharged from the ED are scheduled to follow up with a primary care physician or specialist to continue the diagnostic process or address evolving conditions after an ED visit [3,4]. As emergency medicine (EM) continues to see improvements in medical care for patients who do not need acute hospitalization, the field has become increasingly reliant on follow-up care to ensure patients' full recovery. Follow-up care in EM has garnered significant attention, as about half of all malpractice claims against EM physicians are related to the quality or presence of follow-up care [5]. However, despite its growing importance, only about 26 %–56 % of patients adhere to the follow-up plan that an ED physician prescribes [6].

Patient non-adherence to follow-up plans is multifaceted, with many opting out of continued care due to perceived recovery [6]. Patients who do not fully understand their discharge instructions may fail to manage their conditions effectively post-discharge, leading to complications and readmission. Studies have shown that enhanced discharge education can significantly reduce readmissions [5,7]. Research conducted by Engel et al. [8] on patients recently discharged from U.S. emergency departments revealed that the most common parts of clinical care that patients do not fully understand and adhere to are home care and return care instructions. Beyond patients' adherence to follow-up plans, however, there is often a lack of clarity in the plans developed by EM physicians. Boockvar et al. [9] found that only 45 % of patients discharged from the ED received instructions about their post-discharge care. Due to a lack of clear patient-provider and provider-provider communication about follow-up care, many patients return to the ER due to worsening medical conditions, leading to readmission rates within 30 days post-discharge of around 14 % [10]. Establishing comprehensive and clear follow-up care plans can alleviate some of the pressures that EDs currently face due to overcrowding through decreasing readmissions to the ED.

The proliferation of out-of-hospital tools has allowed for a greater capacity for post-discharge care. For example, remote monitoring has become an especially effective way to monitor patients after discharge through smartphone apps, tele-education, and teleconsultation [11]. However, there currently is no method to assign discharge priorities to these resources, and the quality of post-discharge care is ultimately limited by time and resource constraints [12]. Inspired by systems like the Emergency Severity Index (ESI), a triage tool widely used in the ED by 70 % of large hospitals in the US [[13], [14], [15]], there is significant potential to develop a comparable approach for post-discharge care, using an algorithm that utilizes risk stratification to allocate resources based on severity-based priorities. The objective of this study is to develop and validate the Discharge Severity Index (DSI), a tool designed to predict the risk of post-discharge readmissions and optimize the allocation of healthcare resources for follow-up care based on risk stratification.