Severe Mental Illness and Non-specific Abdominal Pain in the Emergency Department: A Multi-institutional Database Study

Abstract Introduction: Abdominal pain is a common cause of emergency department (ED) visits, and non-specific abdominal pain (NSAP) accounts for a large proportion of diagnoses. Patients with severe mental illness (SMI) are particularly vulnerable due to their atypical disease presentation and high comorbidity rates. Previous studies have reported higher ED revisit rates and delayed diagnoses in patients with SMI and NSAP. This study aimed to evaluate ED management, unscheduled ED revisit rates, and short-term adverse outcomes in patients with SMI and NSAP.Methods: Relying on the Chang Gung Research Database (CGRD), we selectively used data from January 1, 2007, to December 31, 2017. Diagnoses of NSAP and SMI were confirmed by combining the ICD codes with relevant medical records. The non-SMI group was matched at a ratio of 1:3 using a Greedy algorithm. The outcomes were ED management, 72-hour unscheduled ED revisits, and 7-day adverse events.Results: A total of 233,671 patients from seven hospitals over a span of 11 years were recruited; among them, 98,722 were excluded based on the inclusion criteria, leaving 134,949 patients for analysis. The SMI group had more comorbidities, a higher rate of 72-hour unscheduled ED revisits, and was more likely to receive analgesics, but less likely to undergo laboratory tests and CT scans. Patients without SMI were more likely to be admitted to the ward and undergo invasive abdominal procedures within seven days after index ED discharge. No significant differences were found in ICU admission, abdominal surgery, or in-hospital mortality between the two groups.Conclusion: Our study demonstrated that patients with SMI and NSAP had a higher rate of 72-hour unscheduled ED revisits, but this did not lead to higher short-term adverse outcomes. Although NSAP is considered a safe diagnosis for both the general population and patients with SMI, the higher rate of unscheduled ED revisits suggests the need for better healthcare interventions to eliminate health disparities in this vulnerable group.