The Association Between Medicare Eligibility on Elective Procedures and Hospital Transfers: A regression discontinuity design applied to the National Inpatient Sample

Introduction Access to affordable health coverage for individuals aged 51 and older, particularly those transitioning out of employer-sponsored insurance or with existing health conditions, is challenging in the United States. This study investigates the potential impact of lowering the Medicare eligibility age on healthcare utilization, focusing on elective procedures among late middle-aged individuals. Previous studies indicate significant increases in healthcare utilization around the Medicare eligibility threshold, but a national-level analysis is needed to understand the implications of policy changes in Medicare eligibility. Methods This retrospective cohort study utilized 2019 data from the National Inpatient Sample (NIS), encompassing over seven million hospital stays and covering more than 97% of the U.S. population. We compared two groups: uninsured patients aged 63-64 and Medicare-insured patients aged 65-66. The analysis focused on nine common elective surgical procedures, employing a regression discontinuity design to minimize confounding. Patients were exactly matched on several variables, including reason for hospitalization, sex, race, and hospitalization type (elective vs. emergent). Results The matched cohort, after exact matching, included 70,916 admissions (47,262 from Medicare patients aged 65-66 and 23,654 from uninsured patients aged 63-64). The study found significantly higher utilization rates of elective procedures, including cataract surgery, glaucoma surgery, joint replacement, and spinal fusion, among the Medicare-eligible group compared to the younger, uninsured group. Rates of elective procedures approximately doubled post-eligibility for Medicare. Additionally, being below the Medicare eligibility age was associated with decreased odds of undergoing these procedures and increased odds of hospital transfers. Discussion Lowering the Medicare eligibility age could lead to increased access to elective medical procedures for late middle-aged individuals, potentially reducing delays in treatment and associated complications. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data used for this analysis is available from HCUP at [www.hcup-us.ahrq.gov/nisoverview.jsp][1]. . [1]: https://www.hcup-us.ahrq.gov/nisoverview.jsp