Indeed, nearly one in four (23 percent) describe reviewing their Medicare plan annually as among the top two most unpleasant things, including getting a colonoscopy.

“Some do not re-evaluate because they claim their current plan meets their needs; others feel frustrated with the process and don’t look forward to reviewing it,” the authors write. “But not reassessing their coverage annually may cause many to lose out on the best deals available to them.”

While men are more likely than women (28 percent vs. 19 percent) to feel shopping for a Medicare plan is “a walk in the park,” women are more likely (22 percent vs. 17 percent) to view it as “an awful experience.” Their negative feelings may also be tied to the cost: Women are more likely than men (44 percent vs. 35 percent) to find healthcare expenses to be burdensome.

“The biggest risk for seniors is the tendency to look in the rearview mirror when it comes to their health, instead of looking at the road ahead,” saysBart Astor, eldercare expert and author of the book, “AARP Roadmap for the Rest of Your Life.”

“Many seniors are either coming into Medicare with more health conditions than previous generations, or are likely to experience a change in their health status in the coming year,” Astor says. “With most Medicare plans changing from year to year, seniors may be putting their savings at risk by relying on their past rather than planning to protect their future, a decision that could present a prescription for disaster.”

He cites statistics from the Kaiser Family Foundation, which show that out-of-pocket expenses for health care accelerate with age, and the percentage of healthcare spending doubles from age 65 – 69 to age 70-79 – even though 63 percent of respondents say they don’t review their Medicare plan for the best deal because they were satisfied with the plan they were on previously.

“The emergence of a new epidemic among seniors – an epidemic of apathy when it comes to Medicare coverage - could have a significant impact on the financial health of seniors," says Michael Polen, WellCare's executive vice president, Medicare and operations.

“There are numerous benefits beyond just cost, network and formulary that play a critical role in seniors' care, including rehabilitation services, diagnostic services and care for people experiencing cognitive and neurological decline, all of which are experiencing an increase in demand, but that aren't necessarily fully covered by traditional Medicare,” Polen says.

Despite the difficulties they encounter in reviewing their coverage, most seniors (57 percent) choose to review their plan by themselves rather than seek out help.

“There are numerous ancillary services -- for example, 24-hour assistance lines and local help centers with trained professionals -- that can help seniors through the process, whether they want to work through it themselves, or if they choose to do so with help,” says Astor.

“Regardless of the method, there's still time, and it’s critical that, in the current environment, seniors take steps to assess the state of traditional Medicare, the changes that have occurred to Medicare Advantage, and be honest with themselves about preparing for their needs,” he says.