Aims and Objectives The prevalence of multimorbidity, the presence of two or more long-term conditions (LTCs) is increasing, and it is associated with poor health outcomes. Multimorbidity is likely to impact on care delivery in emergency department(ED) settings due to time-critical decision-making in the context of patient complexity. This study describes the impact of multimorbidity in patients attending ED on 30-day mortality and other patient-centred outcomes in an ED setting.

Method and Design This was a cohort study of adults attending EDs in the NHS Lothian region of Scotland between 2012 and 2019, using linked records including ED attendance records, hospital discharge records, cancer registry and national death records. Multimorbidity was defined as two or more Elixhauser conditions. Multivariable logistic regression was used to assess the association of multimorbidity on 30-day mortality (primary outcome), time spent in ED (linear regression), hospital admission and 7-day ED reattendance (secondary outcomes). Primary analysis was stratified by age (<65 vs >=65 years), and associations between individual LTCs and 30-day mortality were reported.

Results and Conclusion There were 1,273,937 attendances to EDs in the region during the study period, corresponding to 451,291 patients. The prevalence of multimorbidity was 9.6% (n=43504). After adjusting for confounding, multimorbidity was associated with higher 30-day mortality (8.2% vs 1.2%, OR 1.81 (1.72-1.91),p<0.001), longer time spent in department (mean difference 16 minutes (16-17 minutes), p<0.001), higher rate of hospital admission (60.1% vs 20.5%, OR 1.81 (1.76-1.86),p<0.001) and higher 7-day ED reattendance in those discharged from ED (7.8% vs 3.5%, OR 1.41 (1.32-1.50),p<0.001) . Magnitude of associations between multimorbidity and all outcomes were more pronounced in patients <65 years old.

Almost one in ten patients presenting to ED were multimorbid. Multimorbidity was strongly associated with adverse outcomes and these associations were more pronounced in younger patients. Patients with multimorbidity in ED settings may benefit from improved recognition and tailored care pathways.