Background:  A small population of patients disproportionately consume an increasing share of medical resources.  These super-utilizers often have complex medical and psychosocial conditions that require carefully coordinated, individualized care.  As this population drives unplanned readmissions, programs to reduce readmissions may create unintended incentives to direct super-utilizers to another hospital system.   This study was designed to investigate the rate and impact of inter-hospital transfer on the super-utilizer population.

Methods:  A large inpatient and emergency room database was generated using Health Care Utilization Project’s State Inpatient (SID) and Emergency Department (SEDD) databases from 5 states (FL, IA, NY, UT, VT ) from 2011-2013.  Super-utilizers were identified if patients had more than 4 inpatient stays in one year and at least one 30-day readmission.  Inter-hospital transfers (IHT) were extracted from this dataset.  The primary outcome was time to readmission or inpatient death within 90 days of transfer by cox proportional hazards while controlling for age, demographics, insurance payer, and comorbidities.

Results: Approximately 225,000 super-utilizers were identified contributing to 1.6 million inpatient visits.  Super-utililzers had a significantly higher IHT rate than the general population (OR 1.4, 95% CI 1.28–1.47, p<0.001) when adjusting for patient demographics and comorbidities.  21,561 patients with 89,333 discharges underwent IHT at least once during the study period.  Patients were classified into three categories:  transferred to a hospital where they had prior care (Continuity, n=17,613; 66,812 encounters) transferred to a new hospital with subsequent visits elsewhere (Discontinuity, n=2,173; 14,441 encounters), and transferred to a new hospital with subsequent visits at the accepting facility (Transition, n=1,775; 8,080 encounters).  Patient demographics, comorbidities, and insurance payer were similar between groups.  Adjusted inpatient mortality and readmissions was highest for the discontinuity group (HR 1.82, 95% CI 1.7-1.9, p<0.001).  Remarkably, patients who transitioned to a new hospital had a markedly reduced readmission or death rate (HR 0.33, 95% CI 0.30–0.37, p<0.001) when compared to those with continuity. 

Conclusions:  This study demonstrates super-utilizers are more likely to be transferred between inpatient facilities.  Discontinuity of care generates an increase in both mortality and readmission rates while  patients who establish care at a new hospital have markedly reduced readmission rates.  This result may be driven by comprehensive programs at tertiary referral centers to manage complex patients, or selection bias toward accepting or establishing subsequent care for lower risk patients by the receiving hospital.  This study demonstrates that a focus on readmission rates as a quality measure is problematic as discontinuity may be incentivized with subsequent poor outcomes.