Mental illness comorbidity significantly impacts surgical outcomes for emergency surgical patients

Background: Whilst both mental illness comorbidity and the delivery of emergency surgery are commonplace in Australia, there is little evidence investigating any link between them. As such, this study examines the emergency surgical outcomes for patients with mental illness compared to other surgical patients within the Australian public surgical system. Methods: Retrospective cohort study involving adult emergency and elective surgical patients treated at three public hospitals in Sydney, Australia between 2018 and 2019. Patients were identified using ICD-10 diagnosis codes, and grouped by those with decompensated mental illness, chronic depression, or those without mental illness. Outcome measures included those within the emergency department (ED), along with in-hospital mortality and surgical outcomes. Results: Of 48 338 total patients, 31 890 (66.0%) had elective and 16 448 (34.0%) had emergency surgery. For patients with decompensated mental illness, only 228 (0.7%) had elective whilst 425 (2.6%) had emergency surgery. Their outcomes for this surgery type included being triaged significantly higher (Cat 1 or 2, 34% vs. 15%) and longer ED stays (8.3 vs. 6.6 h). They also had significantly more post-operative complications (26% vs. 8%) and total days in hospital (33.8 vs. 8.5 days). There was no significant difference for in-hospital mortality. Conclusion: Patients with mental illness are significantly more likely to have emergency surgery including presenting to the ED with more acute physical illness and to experience worse surgical outcomes compared to other surgical patients for every measure analyzed except mortality. There is considerable opportunity to further investigate how these differences might be improved.