Association between waiting times and short term mortality and hospital admission after departure from emergency department: population based cohort study from Ontario, Canada

Abstract

Objective: To determine whether patients who are not admitted to hospital after attending an emergency department during shifts with long waiting times are at risk for adverse events.

Design: Population based retrospective cohort study using health administrative databases. Setting High volume emergency departments in Ontario, Canada, fiscal years 2003-7.

Participants: All emergency department patients who were not admitted (seen and discharged; left without being seen).

Outcome measures: Risk of adverse events (admission to hospital or death within seven days) adjusted for important characteristics of patients, shift, and hospital.

Results: 13,934,542 patients were seen and discharged and 617,011 left without being seen. The risk of adverse events increased with the mean length of stay of similar patients in the same shift in the emergency department. For mean length of stay ≥ 6 v <1 hour the adjusted odds ratio (95% confidence interval) was 1.79 (1.24 to 2.59) for death and 1.95 (1.79 to 2.13) for admission in high acuity patients and 1.71 (1.25 to 2.35) for death and 1.66 (1.56 to 1.76) for admission in low acuity patients). Leaving without being seen was not associated with an increase in adverse events at the level of the patient or by annual rates of the hospital.

Conclusions: Presenting to an emergency department during shifts with longer waiting times, reflected in longer mean length of stay, is associated with a greater risk in the short term of death and admission to hospital in patients who are well enough to leave the department. Patients who leave without being seen are not at higher risk of short term adverse events.

Conflict of interest statement

Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: AG received financial support from the Ontario Ministry of Health and Long Term Care for the submitted work and she and MS receive salary support from the Canadian Institute for Health Research; the authors have no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

Fig 1 Adjusted odds ratios (95% confidence intervals) for death and admission to hospital within seven days of emergency department visit among all non-admitted (seen and discharged and left without being seen) high acuity patients (Canadian triage and acuity scale levels 1 to 3). Odds ratios adjusted for triage level, age group, sex, calendar month, income fifth, urban/rural community, No of visits to emergency department in previous year, chief complaint, time/day of shift

Fig 2 Adjusted odds ratios (95% confidence intervals) for death and admission to hospital within seven days of emergency department visit among all non-admitted (seen and discharged and left without being seen) low acuity patients (Canadian triage and acuity scale levels 4 to 5). Odds ratios adjusted for triage level, age group, sex, calendar month, income fifth, urban/rural community, No of visits to emergency department in previous year, chief complaint, time/day of shift