Health policy and clinical practice/original research
Disequilibrium Between Admitted and Discharged Hospitalized Patients Affects Emergency Department Length of Stay

https://doi.org/10.1016/j.annemergmed.2009.04.017Get rights and content

Study objective

Most patients are admitted to the hospital through the emergency department (ED), and ED waiting times partly reflect the availability of inpatient beds. We test whether the balance between daily hospital admissions and discharges affects next-day ED length of stay.

Methods

We conducted a cross-sectional study of hospitals in metropolitan Toronto, served by a single emergency medical services provider in a publicly funded system. During a 3-year period, we evaluated the daily ratio of admissions to discharges at each hospital and the next-day median ED length of stay in the same hospital by using linear regression.

Results

Across hospitals, the daily mean (SD) 50th percentile ED length of stay averaged 218 (51) minutes. As the inpatient admission-discharge ratio increased or decreased, next-day ED length of stay changed accordingly. Compared with ratios of 1.0, those less than 0.6 were associated with an 11-minute (95% confidence interval [CI] 5 to 16 minutes) shorter next-day median ED length of stay; at admission-discharge ratios of 1.3 to 1.4, ED length of stay was significantly prolonged by 5 minutes (95% CI 3 to 6 minutes). Admission-discharge ratios on weekends and among medical inpatients had a stronger influence on next-day ED length of stay; effects were also greater among higher-acuity and admitted ED patients.

Conclusion

Disequilibrium between the number of admitted and discharged inpatients significantly affects next-day ED length of stay. Better matching of daily hospital discharges and admissions could reduce ED waiting times and may be more amenable to intervention than reducing admissions alone. The admission-discharge ratio may also provide a simple way of tracking and enhancing hospital system performance.

Introduction

More than 119 million emergency department (ED) visits occurred in the United States in 2006, a 32% increase during the last decade.1 Recently, ED crowding and timeliness of care have become major concerns.2 Lengthy ED waiting times are associated with an increased likelihood that a patient will leave without being seen3 and of ambulance diversion.4 Prolonging ED length of stay may compromise quality of care,5 including delayed fibrinolysis for myocardial infarction6 and stroke7 and poorer outcomes in trauma patients.8 Conversely, reducing ED length of stay leads to greater patient satisfaction9 and potential cost savings.10, 11

Between 50% and 75% of all patients are admitted to hospital though the ED.12 Overall, about 1 in 8 ED visits results in hospital admission, and the rate is higher in higher-volume urban centers.1 ED function is intimately related to inpatient services and access to beds13, 14, 15, 16: when resources are limited, availability of inpatient beds for patients admitted from the ED is diminished.17, 18 Elective surgery can compete for the same inpatient resources and thus also affect bed availability. A relative excess of inpatient admissions compared with discharges on a given day may produce a state of “disequilibrium,” reducing the availability of beds for urgent admissions from the ED.15 Hospital occupancy only indirectly reveals this real-time equilibrium because some inpatients were admitted days or weeks before.

We theorized that the effect of inpatient bed availability on ED delays depends on the extent to which daily new admissions to hospital are matched with new discharges. We postulated that a high ratio of daily inpatient admissions to discharges would increase next-day ED length of stay and vice versa. We hypothesized that this effect would be most pronounced among high-acuity ED patients (who are more likely to require inpatient beds) and those requiring admission to the hospital, particularly medical (rather than surgical) admissions.

Section snippets

Setting

We conducted a cross-sectional study of all adult and pediatric ED visits in acute care facilities from April 2004 to March 2007 in the greater Toronto area in the province of Ontario, population 5.1 million, the seventh largest metropolitan area in North America. All 21 participating EDs are part of a publicly funded hospital system, with no user fees, and remain open continuously. Ambulances are administered by a single out-of-hospital care provider, which operates a centralized dispatch

Results

During the 3-year period of study, we identified 22,995 hospital-days of observation among 21 EDs. The overall mean (SD) 50th percentile ED length of stay was 218 (51) minutes. Inpatient and next-day ED characteristics according to admission-discharge ratio are shown in Table 1. admission-discharge ratios were positively associated with inpatient length of stay, elective surgery variability, and admission rates from the ED and were considerably higher on weekdays compared with weekends. There

Limitations

This was a large multicenter study in a single, publicly funded health care system integrated with a single emergency medical services (EMS) system. Findings were robust across different outcome measures and different patient types. Although we adjusted for a number of potentially important confounders, we could not account for the availability of hospital beds or hospital occupancy. However, in high-volume hospitals in which long ED waiting times are common, high hospital occupancy levels are

Discussion

During periods of disequilibrium between the number of patients admitted and discharged from the hospital, we observed significant changes in next-day ED length of stay. Lower admission-discharge ratios were typically associated with a reduction in ED length of stay, whereas ratios above 1.0 were associated with a longer next-day ED length of stay. This effect was more pronounced among higher-acuity and admitted patients, was particularly evident on weekends, and was driven by medical

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    Provide feedback on this article at the journal's Web site, www.annemergmed.com.

    Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. Supported by a grant from the Peter Lougheed Medical Research Foundation. Drs. Ray and Bell are supported by Canadian Institutes for Health Research New Investigator Awards.

    Supervising editor: Donald M. Yealy, MD

    Author contributions: MJV, JGR, CB, BC, and MJS participated in the design of the study. TAS took primary responsibility for the design of the analysis. All authors contributed to the article and take responsibility for the content. MJV and MJS take responsibility for the paper as a whole.

    Publication date: Available online June 25, 2009.

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