Insurance Coverage Predicts Mortality in Patients Transferred Between Hospitals: a Cross-Sectional Study

Background: Patients transferred between hospitals are at high risk of adverse events and mortality. The relationship between insurance status, transfer practices, and outcomes has not been definitively characterized. Objective: To identify the association between insurance coverage and mortality of patients transferred between hospitals. Design: We conducted a single-institution observational study, and validated results using a national administrative database of inter-hospital transfers. Setting: Three ICUs at an academic tertiary care center validated by a nationally representative sample of inter-hospital transfers. Patients: The single-institution analysis included 652 consecutive patients transferred from 57 hospitals between 2011 and 2012. The administrative database included 353,018 patients transferred between 437 hospitals. Measurements: Adjusted inpatient mortality and 24-h mortality, stratified by insurance status. Results: Of 652 consecutive transfers to three ICUs, we observed that uninsured patients had higher adjusted inpatient mortality (OR 2.67, p = 0.021) when controlling for age, race, gender, Apache-II, and whether the patient was transferred from an ED. Uninsured were more likely to be transferred from ED (OR 2.3, p = 0.026), and earlier in their hospital course (3.9 vs 2.0 days, p = 0.002). Using an administrative dataset, we validated these observations, finding that the uninsured had higher adjusted inpatient mortality (OR 1.24, 95% CI 1.13–1.36, p < 0.001) and higher mortality within 24 h (OR 1.33 95% CI 1.11–1.60, p < 0.002). The increase in mortality was independent of patient demographics, referral patterns, or diagnoses. Limitations: This is an observational study where transfer appropriateness cannot be directly assessed. Conclusions: Uninsured patients are more likely to be transferred from an ED and have higher mortality. These data suggest factors that drive inter-hospital transfer of uninsured patients have the potential to exacerbate outcome disparities.