Background:  As electronic health records (EHR) become ubiquitous, the impact on patient outcomes remains largely unknown.  One major communication barrier during patient transfers is the lack of interoperability between EHR systems.  Inter-hospital transfers involve transitioning high acuity patients between hospital systems that may not be able to directly communicate with one another, creating the ideal environment to study the impact of EHR interoperability on patient outcomes. 

Methods:  We performed a retrospective single center observational study of all patients transferred to an academic tertiary care facility from August 2011 through March 2015.  Degree of EHR interoperability was dichotomized into two categories: complete and incomplete integration.  Complete integration was defined as accessible patient level data at any point in real-time during the transition.  Incomplete integration was defined as patient level data accessible after arrival at the accepting institution (i.e. Epic CareEverywhere functionality).  The primary outcome was 90-day all-cause mortality, with length of stay (LOS) and inpatient mortality as secondary outcomes.  Adjustments were made for age, demographics, transfer timing, and severity of illness employing MPM0-III and Charleson Comorbidity Index.

Results:  During the study period 4689 patients arrived from hospitals with complete EHR integration. An additional 5184 patients arrived from facilities with incomplete integration.   Patients with complete EHR integration were slightly older (57.5 vs 54, p< 0.001), and more frequently Caucasian (92.5% vs 82.0%, p < 0.001), but were otherwise similar.  Patients transferred between hospitals with complete EHR integration arrived with significantly lower MPM0-III scores (p<0.001), and were less likely to be in shock (p<0.001) or hemodynamically unstable on admission.  After controlling for comorbidities and age, complete EHR integration was associated with a significant reduction in 90 day all-cause mortality (HR 0.78, 95% CI 0.57 – 0.86, p < 0.001), inpatient mortality (OR 0.68, 95% CI 0.49 -0.78, p < 0.001), and reduced length of stay (5.5 vs 8.5, p < 0.001).  To ensure the survival benefit was not driven by selection of less acute patients, cases where transfer was initiated but not completed were compared and unadjusted ninety day mortality was not different between the complete and incomplete integration groups (p=0.748).

Conclusions:  High quality hand-offs and safe transitions of care appear to be improved with real-time comprehensive information availablity, which aids in ongoing decision making during the transfer process.  When comparing two levels of EHR integration, seamless interoperability was superior in terms of resource utilization, inpatient mortality, and 90 day all cause mortality.