If retired teacher Anna Jensen sticks with her Humana Medicare health plan, her drug costs will surpass $3,000 next year, up $120 from this year.

"Well, that's not so bad," said Jensen, who moved to a Bloomington apartment two years ago to be closer to her daughter. "You expect prices to rise at least a little."

Or she could cut that increase to just $40 if she switched to a UCare plan -- the cheapest health plan possible for her set of drugs -- as open enrollment starts Monday for Medicare health and drug plans for 2013.

"Oh, I've heard UCare is pretty good, but I think I'll stick with what I've got," she said last week. "To be honest, I've never really done comparison shopping. I know I could, but I've just stayed with Humana."

Jensen's experience is the norm for the 480,000 Minnesotans with Medicare drug coverage.

"We know many people can do better," said Jean Wood, director of aging and adult services at the Minnesota Department of Human Services. "But we also know that most just stay with the plan they've got."

A recent study of 12,000 people with Medicare drug coverage showed that only 5 percent of them had the cheapest among scores of plans available, and could have saved $654 on average this year had they switched plans last fall.

That could mean that Minnesotans might have saved about $315 million this year, according to the study by online health insurance sales firm PlanPrescriber.com.

At least 15,000 Minnesotans will be forced to change plans because 13 drug plans no longer will offer coverage next year, while 14 new ones will start, Wood said.

Overall, Minnesota beneficiaries can choose from 32 plans offering drug-only coverage, 27 Medicare Advantage plans covering health and drug costs, and three "special needs" comprehensive plans, for people with lung diseases, dementia, or with diabetes or heart disease.

Double costs for same drugs

An analysis by the nonprofit Kaiser Family Health Foundation found that average premiums for the stand-alone plans will be unchanged next year.

But the cost to individuals can vary sharply from plan to plan, and may rise or fall next year.

For instance, Jensen's Humana plan this year is the third cheapest. Had she been on the Medicare Blue health plan, her drug costs this year would have more than doubled, to $6,450.

The Humana monthly premium actually is $6 more than the Blue plan. But under the Blue plan she must pay the full monthly price of $364 for her most expensive drug, an injectable diabetes drug called Byetta, because it is not on the list of drugs Blue covers. Under her Humana plan, she pays less than half the cost.

Here are some basics:

Open enrollment: Oct. 15 to Dec. 7. You can change plans without restriction. If you do nothing, you automatically will stay in your current plan.

Picking a plan on your own: The only way to compare the costs of each plan is on the Internet. The most complete tool is on the Medicare website, although other comparison tools are available.

Go to Medicare.gov, click on "find health and drug plans" and enter the ZIP code or Medicare number of the beneficiary. Enter the drugs and dosages, the pharmacy, then choose whether to look at drug-only plans, health plans that include drugs or health plans without drug coverage.

The plans are listed from lowest to highest total cost, with lots of detail.

For help: Call Medicare any time at 1-800-633-4227 (TTY/TDD 1-877-486-2048); or the Minnesota Senior LinkAge Line at 1-800-333-2433 weekdays from 8 a.m. to 4:30 p.m. Either service can help you compare and enroll in plans, and help people who qualify for a low-income subsidy.

The LinkAge Line also can tell you where to find trained volunteers at nearby public sites, and can dispatch volunteers to visit home-bound beneficiaries.

The Minnesota Board on Aging will publish Minnesota Health Care Choices, a free guide to the plans, available by Nov. 1 from the LinkAge Line, senior centers and elsewhere.

Warren Wolfe • 612-673-7253