This is the first study to investigate ED management, 72-hour unscheduled ED revisit rate, and short-term adverse outcomes in patients with SMI who visited the ED with a discharge diagnosis of NSAP. The findings revealed a higher 72-hour unscheduled ED revisit rate in the SMI group, but no poorer short-term outcomes, including ward admission, ICU admission, surgery or invasive procedures within seven days, and in-hospital mortality in this population.
Digestive system diseases are the most common diagnostic category leading to unscheduled ED revisits, which may be attributed to a variety of differential diagnoses and diverse clinical presentations (18, 19). According to a study in 2014, Meltzer et al. reported that major depressive disorder is associated with an increased risk of ED revisits in patients with NSAP (8). Our results are consistent with those of previous studies and provide further evidence that not only patients with major depressive disorder but also other patients with SMI who present to the ED with NSAP are at increased risk of subsequent 72-hour unscheduled ED revisits. This relationship may be explained by disease and healthcare system factors. Functional gastrointestinal disorders (FGID) are characterized by gastrointestinal symptoms without a demonstrable etiology, and have been shown to be highly associated with SMI and ED utility (20-23). However, the diagnosis of FGID is mainly based on criteria that require stepwise exclusion, making it difficult to diagnose in an ED setting (24). In addition, the ED plays a crucial role in the healthcare system, especially for the underserved vulnerable population who may have limited access to other healthcare services, such as outpatient departments. In particular, patients with SMI are less likely to have access to established healthcare services and have a higher rate of ED utilization (25). The higher prevalence of FGID and increased ED utilization among patients with SMI may be important factors contributing to the higher 72-hour unscheduled ED revisit rate in this group.
Although patients with NSAP and SMI have a higher 72-hour unscheduled ED revisit rate, there were no obvious short-term adverse outcomes, including ward admission, ICU admission, surgery or invasive procedures within seven days, and in-hospital mortality. Patients received fewer laboratory and CT studies during the index ED visit, resulting in a lower total ED expenditure. Despite this, there were no apparent adverse short-term outcomes associated with the reduced testing and lower costs. NSAP is generally considered a benign diagnosis in the ED, and a 2020 study found that only 0.7% of revisiting patients with a previous discharge diagnosis of NSAP required hospitalization, and only 0.06% needed immediate surgery (26). Our study revealed higher hospitalization rates of 1.1% and 0.37%, respectively, in patients who underwent abdominal surgery. The differences in rates may be attributed to different healthcare and insurance systems as well as the different definitions used in the studies (27). For instance, our study defined any abdominal operation within the acute phase, whereas Sarristo et al. defined abdominal surgery only in urgent conditions (e.g., acute mesenteric ischemia and bowel perforation). However, despite these differences, our study concurs with a previous study demonstrating that NSAP is a safe diagnosis in current clinical practice in the ED, both in the overall population and in patients with SMI, given its low short-term adverse outcomes.
Although a higher rate of 72-hour unscheduled ED revisits did not contribute to higher short-term adverse outcomes in patients with SMI and NSAP, it may reflect inadequate ED management. The 72-hour unscheduled ED revisit rate is considered a healthcare quality indicator, as unscheduled ED revisits are associated with ED crowding, higher healthcare expenditure, and poorer medical experiences (28-30). Previous studies have also revealed that mental illness is a risk factor for unscheduled ED revisits and have attributed this to unclear discharge instructions, inefficient discharge systems, and inadequate post-ED follow-ups (31-33). To address this issue, various strategies such as multidisciplinary approaches, integrated discharge systems, and post-ED care programs have been found to be effective in reducing unscheduled ED revisits (34, 35). Reducing unscheduled ED revisits may have a particularly profound effect on vulnerable patient populations with frequent ED visits, and further improve healthcare equity (36).