The association between socioeconomic status and outcomes in critical illness: A national cohort study of emergency admissions to critical care units in Scotland 2010-2021.

Background: Socioeconomic inequalities in chronic disease management and outcomes are well-established. Their association with critical illness management and outcomes is less clear. This study aimed to investigate the association between socioeconomic status and outcomes following emergency admission for critical illness.

Methods: Three Scotland-wide health databases were linked: the Scottish Intensive Care Society Audit Group database (critical care units); the Scottish Morbidity Record 01 (hospital admissions) and death certificates. A retrospective cohort study was conducted on adults (⩾16 years) admitted as an emergency to critical care units between 25th October 2010 and 25th October 2021 inclusive. Cox proportional hazards models were used to investigate the association between area-based socioeconomic status (Scottish Index of Mortality (SIMD) decile) and all-cause mortality, adjusting for potential confounders: age, sex, comorbidities, illness severity, and diagnostic group. Secondary outcomes included unit and hospital lengths of stay, and emergency hospital readmissions.

Results: Overall, 50,914 patients were included in the cohort. Those in the least deprived decile were less likely to die (_adjHR 0.85, 95% CI 0.79-0.92), had 19% longer critical care unit stays (95% CI 13-26) and a 12% longer hospital stays (95% CI 7%-18%). Over the subsequent year, the least deprived had significantly fewer emergency hospital re-admissions (_adjIRR 0.73; 95% CI 0.67-0.81).

Discussion: People living in the most deprived communities have worse outcomes following emergency admission to critical care; particularly in the longer term and reinforcing the need to address socioeconomic inequalities in healthcare access and outcomes.