Nearly 13 million people skipped a needed medication or stretched their doses because they couldn’t afford the drug, while millions more went without needed medical treatment because of cost, according to a new study by the Robert Wood Johnson Foundation and the Urban Institute that analyzed data in the years leading up to the pandemic.

Ever-rising health-care costs are most burdensome to people who are low income or uninsured. But health-care affordability is an issue that cuts across generations and income levels: About 2.6 million Medicare beneficiaries skipped or delayed filling a medication prescription because of cost.

Medicare, the publicly funded health program for adults 65 and older and people with disabilities, is often characterized by good coverage with low out-of-pocket costs. But according to analysis by Robert Wood Johnson researchers, out-of-pocket costs for Medicare beneficiaries vary greatly, depending on your medical needs and the type of plan you choose.

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“It’s tragic that millions of people don’t take needed prescription drugs because they can’t afford them,” Katherine Hempstead, senior policy adviser at the Robert Wood Johnson Foundation, said in a statement. “As we recover from COVID-19 and try to create a more equitable society, ensuring that prescription drugs are affordable must be a policy priority.”

Researchers, who studied insurance and cost data from 2018 and 2019 found:

  • About 91% of people with Medicare filled at least one medication prescription during the year, with a median out-of-pocket cost of $178 a year. By comparison, about 62% of privately insured adults under age 65 filled at least one prescription, with a median annual cost of $62.

  • Out-of-pocket prescription costs exceeded $500 a year for about 22% of Medicare beneficiaries and 6% of privately insured adults.

  • About 25% of Medicare beneficiaries spent more than 1% of their income on medications. About 5% of privately insured adults spent 1% or more of their income on medications.

The findings are a reminder why it is so important to review your Medicare plan every year during the annual fall enrollment period, which ends Dec. 7.

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People with Medicare have two options for prescription drug coverage:

  • A Medicare Advantage plan with drug coverage. Medicare Advantage plans are managed by private insurers and may offer extra benefits, like prescription coverage, but often have more limited doctor networks.

  • A stand-alone Part D prescription plan to add on to traditional Medicare. People with traditional Medicare often also buy a supplemental plan to help cover out-of-pocket costs.

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Just because the medications you take were covered this year doesn’t mean they will be next year. Changes to prescription formularies are among the most common tweaks to Medicare plans.

A drug formulary is a list of medications covered by a health plan, organized by “tier.” Plans often require members to try a drug from a lower-level tier before agreeing to pay for a higher-tier drug, or require people to pay more out-of-pocket to access higher-tier medications.

Use Medicare’s online plan-finder tool to estimate drug costs by plan and compare options at medicare.gov/plan-compare.