title: The Role of Medicare's Inpatient Cost-Sharing in Medicaid Entry.
abstract: To isolate the effect of greater inpatient cost-sharing on Medicaid entry among Medicare beneficiaries.
  
  
  
  Medicare administrative data (years 2007-2010) were linked to nursing home assessments and area-level socioeconomic indicators.
  
  
  
  Medicare beneficiaries who are readmitted to a hospital must pay an additional deductible ($1,100 in 2010) if their readmission occurs more than 59 days following discharge. In a regression discontinuity analysis, we take advantage of this Medicare benefit feature to test whether beneficiaries with greater cost-sharing have higher rates of Medicaid enrollment.
  
  
  
  We identified 221,248 Medicare beneficiaries with an initial hospital stay and a readmission 53-59 days later (no deductible) or 60-66 days later (charged a deductible).
  
  
  
  Among beneficiaries in low-socioeconomic areas with two hospitalizations, those readmitted 60-66 days after discharge were 21 percent more likely to join Medicaid compared with those readmitted 53-59 days following their initial hospitalization (absolute difference in adjusted risk of Medicaid entry: 3.7 percent vs. 3.1 percent, p = .01).
  
  
  
  Increasing Medicare cost-sharing requirements may promote Medicaid enrollment among low-income beneficiaries. Potential savings from an increased cost-sharing in the Medicare program may be offset by increased Medicaid participation.
authors.affiliation: Department of Health Policy, Vanderbilt University School of Medicine, Nashville, TN.
authors.forename: Laura M
authors.identifier: 0000-0002-9400-0575
authors.initials: LM
authors.lastname: Keohane
authors.affiliation: Department of Health Services, Policy and Practice, Brown University, Providence, RI.|Center of Innovation in Long-Term Services and Supports for Vulnerable Veterans, Providence VA Medical Center, Providence, RI.
authors.forename: Amal N
authors.initials: AN
authors.lastname: Trivedi
authors.affiliation: Department of Health Services, Policy and Practice, Brown University, Providence, RI.|Center of Innovation in Long-Term Services and Supports for Vulnerable Veterans, Providence VA Medical Center, Providence, RI.
authors.forename: Vincent
authors.initials: V
authors.lastname: Mor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017047:Cost Sharing / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D005382:Financing, Personal / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008484:Medicaid / Q000706:statistics & numerical data*; D006278:Medicare / Q000191:economics / Q000706:statistics & numerical data*; D016344:Medicare Part A / Q000191:economics / Q000706:statistics & numerical data; D010359:Patient Readmission / Q000191:economics / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012111:Residence Characteristics; D012959:Socioeconomic Factors; D014481:United States
keywords: Medicaid; Medicare; cost-sharing