Effect of Decreased Emergency Department Access on Patient Outcomes

Grant Description: The researchers examined whether decreased emergency department (ED) access results in adverse patient outcomes or changes in other health indicators. There is a great deal of literature documenting decreased access to EDs. However, there is little empirical evidence linking access to EDs and health outcomes. The researchers used acute myocardial infarction (AMI) patients to examine health outcomes, since AMI patients are relatively homogeneous and the time sensitivity of treatment should be reflected in differences in outcomes. They examined two types of ED access between 1996 and 2005: permanent ED closure and temporary ED closure as measured by ambulance diversion time. The objective of this project was to provide improved understanding of the impact of ED access change in the health care system.

Policy Summary

Changes in Permanent ED Access on AMI Patient Outcomes

The researchers find that ED access deterioration, as measured by increased driving time to the nearest ED, affected a small segment of the population between 1996 and 2005. Small increases in driving time (under 10 minutes) have a small adverse affect on mortality rates, and the magnitude of the effect is greater for those with limited access to hospitals at baseline. Large increases in driving time (over 30 minutes) increase the observed long-term mortality rates among patients who survived to have a hospital admission record, and also change the health profile of admitted patients (such as younger age, and faced with a higher probability of receiving PTCA on the day of admission). However, the observed adverse effects are mostly transitory: all outcomes return to similar levels as the pre-change period after the transition years. These findings suggest that policy planners can minimize the adverse effects during the transition years by providing assistance to ensure adequate capacity of remaining operating EDs in the area, and facilitating the realignment of health care resources during these critical periods.

Effect of Ambulance Diversion on AMI Mortality Rates

Diversion is a signal of a larger access problem in the health care system.  The researchers analyze ambulance diversion in 4 major California counties between 2000 and 2005 and find that the median duration of diversion is 6 hours per day, with 25 percent of hospitals being on divert for 12 hours or more on a given day. The researchers then categorize patients based on whether their nearest ED was on diversion on the day of their ED admission: not on diversion (control group), on diversion for < 6 hours, 6-12 hours, and > 12 hours. The researchers find that there is no difference in AMI mortality rates between the control group and the first two treatment groups where the diversion hours of the nearest ED on teh day of admission is under 12 hours. However, temporary closure due to diversion has an adverse effect on heart attack patients' mortality outcomes when the diversion exceeds 12 hours, and such an effect persists even for long-term mortality rates. Notably, such long diversion hours are more likely to occur in winter and in densely populated metropolitan areas--both factors that are associated with higher ED demand. Currently, county and state policies on ambulance diversion vary widely. The results from this analysis suggest that optimal policy should include provisions that would minimize instances in which hospitals would go on extensive hours of diversion.