The association between hospital overcrowding and mortality among patients admitted via Western Australian emergency departments

Abstract

Objective: To examine the relationship between hospital and emergency department (ED) occupancy, as indicators of hospital overcrowding, and mortality after emergency admission. Design: Retrospective analysis of 62 495 probabilistically linked emergency hospital admissions and death records. Setting: Three tertiary metropolitan hospitals between July 2000 and June 2003. Participants: All patients 18 years or older whose first ED attendance resulted in hospital admission during the study period. Main outcome measures: Deaths on days 2, 7 and 30 were evaluated against an Overcrowding Hazard Scale based on hospital and ED occupancy, after adjusting for age, diagnosis, referral source, urgency and mode of transport to hospital. Results: There was a linear relationship between the Overcrowding Hazard Scale and deaths on Day 7 (r = 0.98; 95% CI, 0.79–1.00). An Overcrowding Hazard Scale > 2 was associated with an increased Day 2, Day 7 and Day 30 hazard ratio for death of 1.3 (95% CI, 1.1–1.6), 1.3 (95% CI, 1.2–1.5) and 1.2 (95% CI, 1.1–1.3), respectively. Deaths at 30 days associated with an Overcrowding Hazard Scale > 2 compared with one of < 3 were undifferentiated with respect to age, diagnosis, urgency, transport mode, referral source or hospital length of stay, but had longer ED durations of stay (risk ratio per hour of ED stay, 1.1; 95% CI, 1.1–1.1; P < 0.001) and longer physician waiting times (risk ratio per hour of ED wait, 1.2; 95% CI, 1.1–1.3; P = 0.01). Conclusions: Hospital and ED overcrowding is associated with increased mortality. The Overcrowding Hazard Scale may be used to assess the hazard associated with hospital and ED overcrowding. Reducing overcrowding may improve outcomes for patients requiring emergency hospital admission.

The association between a prolonged stay in the emergency department and adverse events in older patients admitted to hospital: a retrospective cohort study

“…In the current study, the average daily hospital occupancy was 92.3% and the average arrival density index was 7.6—both figures are highly consistent with the findings by Forster et al 18. In a study of Australian inpatients, a clear linear relationship was demonstrated between an overcrowding hazard scale score of greater than 2 and inpatient mortality, even after adjusting for age, diagnosis, referral source, urgency and mode of transport to the hospital 14. On average, the overcrowding hazard scale in the current study did not exceed 2.…”

“…The first was the “overcrowding hazard scale”, which tests the combined effects of hospital and ED crowding. The possible scores range from 1 to 9, with the higher score indicating greater crowding 14. The second was the “arrival density index”, designed to measure how busy the ED was when a patient arrived (ie, number of patients who arrived in the ED in the preceding hour for every patient).…”

Emergency department crowding

“…Finally, three studies have looked at mortality associated with crowding. Two papers from Australia have shown increased mortality in patients admitted from overcrowded departments,34 76 although the definition used in one of these papers is a little hazy. Two papers I found,77 78 along with two reported by Pham et al ,67 failed to find an association between ambulance diversion and increased mortality, although the results may be confounded by system factors (even during diversion many centres will still receive critically ill patients).…”

Safety and efficiency of triaging low urgent self-referred patients to a general practitioner at an acute care post: an observational study

“…It has been suggested that most self-referrals can be treated by the GP,1 but exact numbers and research on this topic are missing. This so-called inappropriate use of EDs should be reduced as much as possible, because it results in ‘overcrowding’, longer waiting times, more diagnostic tests and higher costs 6 7…”