Medicare Plan Switching Among Beneficiaries With and Without a History of Cancer

The role of supplemental coverage (eg, Medigap) in Medicare enrollment and disenrollment is understudied among beneficiaries with cancer. Understanding the association between initially selecting a supplement and switching plans is necessary to ensure adequate and affordable coverage for beneficiaries with high-cost health conditions.

To evaluate Medicare plan switching by initial plan selection and history of cancer.

This cohort study used data from the Health and Retirement Study, from 2008 to 2020. Respondents were aged 65 or 66 years at initial Medicare plan selection and completed 2 consecutive surveys. Analyses were conducted from November 2023 to October 2024.

Self-reported initial Medicare plan selection (traditional Medicare [TM] without supplemental coverage, TM plus supplemental coverage, or Medicare Advantage [MA]) and history of cancer.

The primary outcome was self-reported Medicare plan switching in the 2 years after initial plan selection. Modified Poisson regression was used to assess the association between initial Medicare plan selection and plan switching. Models adjusted for baseline sociodemographic and health-related characteristics and were stratified by a history of cancer.

Among 2852 respondents aging into Medicare (1113 male [39.02%]), 1511 (52.98%) initially selected TM plus supplemental coverage and 358 (12.55%) reported a history of cancer. Less than one-third of beneficiaries (786 beneficiaries without a history of cancer [31.52%] and 106 beneficiaries with a history of cancer [29.61%]) switched coverage in the 2 years after initial plan selection. Most beneficiaries switched from TM without supplemental coverage to benefits with greater financial protections; 131 of 227 beneficiaries without a history of cancer (57.71%) switched to MA, and 18 of 27 beneficiaries with a history of cancer (66.67%) switched to TM plus supplemental coverage. Among beneficiaries without a history of cancer, initial selection of MA (adjusted risk ratio [aRR], 0.55; 95% confidence limit [CL], 0.47-0.64) or TM plus supplemental coverage (aRR, 0.63; 95% CL, 0.55-0.72) was associated with a lower probability of switching coverage compared with initial selection of TM without supplemental coverage. Findings were similar for beneficiaries with a history of cancer.

In this cohort study of older adults with and without a history of cancer, initial selection of MA or TM plus supplemental coverage was associated with a low likelihood of switching coverage. Given that benefits with greater financial protections may meet beneficiaries' evolving needs and preferences, policymakers should consider improving the adequacy of TM.