All health care is not local: an evaluation of the distribution of Emergency Department care delivered in Indiana

Abstract

The Emergency Department (ED) delivers a major portion of health care - often with incomplete knowledge about the patient. As such, EDs are particularly likely to benefit from a health information exchange (HIE). The Indiana Public Health Emergency Surveillance System (PHESS) sends real-time registration information for emergency department encounters. Over the three-year study period, we found 2.8 million patients generated 7.4 million ED visits. The average number of visits was 2.6 visits/patient (range 1-385). We found more than 40% of ED visits during the study period were for patients having data at multiple institutions. When examining the network density, we found nearly all EDs share patients with more than 80 other EDs. Our results help clarify future health care policy decisions regarding optimal NHIN architecture and discount the notion that 'all healthcare is local'.

Figure 1.

Process for preparing ED encounter data

Figure 2.

Geographical distribution of the 96 emergency departments participating in Indiana’s Pubic Health Electronic Surveillance System (PHESS) as of Dec-31-2010.

Figure 3.

Distribution of patients stratified by the total number of ED visits. Note that six patients visited the ED more than 300 times and a single patient accumulated 385 visits for the 3-year study period.

Figure 4.

Distribution of patients stratified by the total number of unique EDs visited. Note that one patient visited 38 EDs during the 3-year study period.

Figure 5.

Proportion of visits by patients with data residing in multiple institutions for each individual emergency department. For 26 EDs, more than 50% of the visits were by patients with data in multiple institutions.

Figure 6.

Proportion of patients with data residing in multiple institutions for each individual emergency department. More than 50% of patients at 15 EDs had encounters at other institutions.

Figure 7.

A network diagram illustrating the connectedness among Indiana EDs that participate in PHESS. Circular nodes represent EDs; node size indicates the visit volume; node color indicates the centrality of the ED. The gray edges connecting nodes indicate where patient crossover occurs. EDs that share proportionally larger number of patients are clustered together. While general clusters of “medical trading areas” emerge, the myriad gray edges clearly illustrate how interconnected all EDs are to one another.