Emergency department crowding and mortality in 14 Swedish emergency departments, a cohort study leveraging the Swedish Emergency Registry (SVAR).

OBJECTIVES: There is evidence that emergency department (ED) crowding is associated with increased mortality, however large multicenter studies of high quality are scarce. In a prior study, we introduced a proxy-measure for crowding that was associated with increased mortality. The national registry SVAR enables us to study the association in a more heterogenous group of EDs with more recent data. The aim is to investigate the association between ED crowding and mortality. METHODS: This was an observational cohort study including visits from 14 EDs in Sweden 2015-2019. Crowding was defined as the mean ED-census divided with expected ED-census during the work-shift that the patient arrived. The crowding exposure was categorized in three groups: low, moderate and high. Hazard ratios (HR) for mortality within 7 and 30 days were estimated with a cox proportional hazards model. The model was adjusted for age, sex, triage priority, arrival hour, weekend, arrival mode and chief complaint. Subgroup analysis by county and for admitted patients by county were performed. RESULTS: 2,440,392 visits from 1,142,631 unique patients were analysed. A significant association was found between crowding and 7-day mortality but not with 30-day mortality. Subgroup analysis also yielded mixed results with a clear association in only one of the three counties. The estimated HR (95% CI) for 30-day mortality for admitted patients in this county was 1.06 (1.01-1.12) in the moderate crowding category, and 1.11 (1.01-1.22) in the high category. CONCLUSIONS: The association between crowding and mortality may not be universal. Factors that influence the association between crowding and mortality at different EDs are still unknown but a high hospital bed occupancy, impacting admitted patients may play a role.

Emergency department crowding and hospital transformation during COVID-19, a retrospective, descriptive study of a university hospital in Stockholm, Sweden.

OBJECTIVES: COVID-19 presents challenges to the emergency care system that could lead to emergency department (ED) crowding. The Huddinge site at the Karolinska university hospital (KH) responded through a rapid transformation of inpatient care capacity together with changing working methods in the ED. The aim is to describe the KH response to the COVID-19 crisis, and how ED crowding, and important input, throughput and output factors for ED crowding developed at KH during a 30-day baseline period followed by the first 60 days of the COVID-19 outbreak in Stockholm Region. METHODS: Different phases in the development of the crisis were described and identified retrospectively based on major events that changed the conditions for the ED. Results were presented for each phase separately. The outcome ED length of stay (ED LOS) was calculated with mean and 95% confidence intervals. Input, throughput, output and demographic factors were described using distributions, proportions and means. Pearson correlation between ED LOS and emergency ward occupancy by phase was estimated with 95% confidence interval. RESULTS: As new working methods were introduced between phase 2 and 3, ED LOS declined from mean (95% CI) 386 (373-399) minutes to 307 (297-317). Imaging proportion was reduced from 29 to 18% and admission rate increased from 34 to 43%. Correlation (95% CI) between emergency ward occupancy and ED LOS by phase was 0.94 (0.55-0.99). CONCLUSIONS: It is possible to avoid ED crowding, even during extreme and quickly changing conditions by leveraging previously known input, throughput and output factors. One key factor was the change in working methods in the ED with higher competence, less diagnostics and increased focus on rapid clinical admission decisions. Another important factor was the reduction in bed occupancy in emergency wards that enabled a timely admission to inpatient care. A key limitation was the retrospective study design.

Association Between Hospital Bed Occupancy and Outcomes in Emergency Care: A Cohort Study in Stockholm Region, Sweden, 2012 to 2016.

STUDY OBJECTIVE: We evaluate the importance of hospital bed occupancy for 30-day mortality, inhospital mortality, readmission for inpatient care within 30 days, and revisits to the emergency department (ED) within 7 days among all adult patients visiting the ED. METHODS: This was an observational cohort study including all adult patients visiting 6 EDs in Stockholm Region, Sweden. ED visits from 2012 to 2016 were categorized into groups by hospital bed occupancy in 5% intervals between 85% and 105%. A proportional hazards model was used to estimate adjusted hazard ratios with 95% confidence intervals (CIs). The model was stratified by hospital and adjusted for age, sex, comorbidities, hospital stays in the year preceding the index visit, marital status, length of education, and weekday/weekend timing of visit. RESULTS: A total of 816,832 patients with 2,084,554 visits were included. Mean hospital bed occupancy was 93.3% (SD 3.3%). In total, 28,112 patients died within 30 days, and 17,966 patients died inhospital. Hospital bed occupancy was not associated with 30-day mortality (hazard ratio for highest category of occupancy ≥105% was 1.10; 95% CI 0.96 to 1.27) or inhospital mortality. Patients discharged from the ED at occupancy levels greater than 89% had a 2% to 4% higher risk of revisits to the ED within 7 days. A 10% increase in hospital bed occupancy was associated with a 16-minute increase (95% CI 16 to 17 minutes) in ED length of stay and 1.9-percentage-point decrease (95% CI 1.7 to 2.0 percentage points) in admission rate. CONCLUSION: We did not find an association between increasing hospital bed occupancy and mortality in our sample of 6 EDs in Stockholm Region, Sweden, despite increased length of stay in the ED and a decline in admissions for inpatient care.

Emergency department crowding associated with increased 30-day mortality: a cohort study in Stockholm Region, Sweden, 2012 to 2016.

OBJECTIVES: Emergency department (ED) crowding is a major problem across the world. Studies investigating the association between crowding and mortality are many, but the quality is inconsistent and there are very few large, high-quality multicenter studies that are properly designed to deal with confounding due to case mix. The aim of this study is to investigate the association between ED crowding and 30-day mortality. METHODS: We conducted an observational cohort study at all 7 EDs in Stockholm Region, Sweden 2012-2016. The crowding exposure was defined as the mean hourly ED census during the shift that the exposed patient arrived, divided with the expected ED census for this shift. The expected ED census was estimated using a separate linear model for each hospital with year and shift as predictors. The exposure was categorized in 3 groups: reference (lowest 75% of observations), moderate (75%-95% of observations), and high (highest 5% of observations). Hazard ratios (HR) for all-cause mortality within 30 days were estimated with a Cox proportional hazards model. The model was adjusted for age, sex, triage priority, arrival hour, weekend, arrival mode, chief complaint, number of prior hospital admissions, and comorbidities. RESULTS: 884,228 patients who visited the ED 2,252,656 times were included in the analysis. The estimated HR (95% confidence interval) for death within 30-days was 1.00 (0.97-1.03) in crowding category 75%-95% and 1.08 (1.03-1.14) in the 95%-100% category. CONCLUSIONS: In a large cohort study including 7 EDs in Stockholm Region, Sweden we identified a significant association between high levels of ED crowding and increased 30-day mortality.