LAUSR

OBJECTIVE To examine the effects of Medicare eligibility and enrollment on the use of high-value and low-value care services. DATA SOURCES/STUDY SETTING The 2002-2019 Medical Expenditure Panel Survey. STUDY DESIGN We employed a regression discontinuity design, which exploits the discontinuity in eligibility for Medicare at age 65 years and compares individuals just before and after age 65. Our primary outcomes included use of high-value care services (eight services) and low-value care services (seven services). To examine the effects of Medicare eligibility, we conducted a regression discontinuity analysis. To examine the effects of Medicare enrollment, we used the discontinuity in the probability of having Medicare coverage around the age eligibility cutoff and conducted an instrumental variable analysis. DATA COLLECTION/EXTRACTION METHODS N/A. PRINCIPAL FINDINGS Medicare eligibility and enrollment led to statistically significant increases in the use of only two high-value services: cholesterol measurement [2.1 percentage points (95%: 0.4-3.7) (2.2% relative change) and 2.4 percentage points (95%: 0.4-4.4)] and receipt of the influenza vaccine [3.0 percentage points (95%: 0.3-5.6) (6.0% relative change) and 3.6 percentage points (95%: 0.4-6.8)]. Medicare eligibility and enrollment led to statistically significant increases in the use of two low-value services: antibiotics for acute upper respiratory infection [6.9 percentage points (95% CI: 0.8-13.0) (24.0% relative change) and 8.2 percentage points (95% CI: 0.8-15.5)] and radiographs for back pain [4.6 percentage points (95% CI: 0.1-9.2) (36.8% relative change) and 6.2 percentage points (95% CI: 0.1-12.3)]. However, there was no significant change in the use of other high-value and low-value care services. CONCLUSION Medicare eligibility and enrollment at age 65 years led to increases in the use of some high-value and low-value care services, but there were no changes in the use of the majority of other services. Policymakers should consider refining the Medicare program to enhance the value of care delivered.