BACKGROUND
Integrated healthcare systems are believed to be enabled by the electronic exchange of clinical information. Canada and other national health systems are making substantial investments in information technology, in order to liberate and share clinical information between providers, improve the quality and safety of care, and reduce costs, yet we currently have no way of measuring these information flows, nor of understanding whether they contribute to the integration of care delivery.
METHODS
A literature review and consensus development process (nominal group) were used to provide guidance on system integration measures which are enabled by electronic information exchange. In order to conceptualize the components of electronic information exchange, establish a reference vocabulary for terminology, and guide the development of a questionnaire to gather field data, a formal ontology was developed. Validation of a sub-group of the survey data quality was achieved using the ontology and an unrelated database, demonstrating how ontologies may be used to adapt performance measurement methodologies to systems where constraints such as time-compression, lack of resources or access to needed information are prevalent.
RESULTS
The survey tool gathered cross-sectoral data from a regional health system which populated a summary measure of inter-provider electronic health information exchange (the eHIE), and measured perceptions of system integration from a single health region. The eHIE indicated that 7 -12% of clinical information that could be shared, was being shared electronically in the health region. ANOVA confirmed a significant correlation between the amount of information being exchanged electronically in this system and respondent perceptions of system integration suggesting that the eHIE may be used as a leading indicator for healthcare system integration. 
CONCLUSIONS
It is possible to conceptualize and quantify inter-provider electronic health information exchange. As complex adaptive systems, healthcare systems are dynamic and open to correction; the use of a leading or proximal indicator such as the eHIE may inform effective policy-making and resource allocation in our pursuit of the goal of seamlessly integrated care