Association between Medicare eligibility at age 65 years and in-hospital treatment patterns and health outcomes for patients with trauma: regression discontinuity approach

OBJECTIVE: To determine whether health systems in the United States modify treatment or discharge decisions for otherwise similar patients based on health insurance coverage. DESIGN: Regression discontinuity approach. SETTING: American College of Surgeons’ National Trauma Data Bank, 2007-17. PARTICIPANTS: Adults aged between 50 and 79 years with a total of 1 586 577 trauma encounters at level I and level II trauma centers in the US. INTERVENTIONS: Eligibility for Medicare at age 65 years. MAIN OUTCOME MEASURES: The main outcome measure was change in health insurance coverage, complications, in-hospital mortality, processes of care in the trauma bay, treatment patterns during hospital admission, and discharge locations at age 65 years. RESULTS: 1 586 577 trauma encounters were included. At age 65, a discontinuous increase of 9.6 percentage points (95% confidence interval 9.1 to 10.1) was observed in the share of patients with health insurance coverage through Medicare at age 65 years. Entry to Medicare at age 65 was also associated with a decrease in length of hospital stay for each encounter, of 0.33 days (95% confidence interval −0.42 to −0.24 days), or nearly 5%), which coincided with an increase in discharges to nursing homes (1.56 percentage points, 95% confidence interval 0.94 to 2.16 percentage points) and transfers to other inpatient facilities (0.57 percentage points, 0.33 to 0.80 percentage points), and a large decrease in discharges to home (1.99 percentage points, −2.73 to −1.27 percentage points). Relatively small (or no) changes were observed in treatment patterns during the patients’ hospital admission, including no changes in potentially life saving treatments (eg, blood transfusions) or mortality. CONCLUSIONS: The findings suggest that differences in treatment for otherwise similar patients with trauma with different forms of insurance coverage arose during the discharge planning process, with little evidence that health systems modified treatment decisions based on patients’ coverage.