THURSDAY, Oct. 11 (HealthDay News) -- For Medicare participants, choosing the right prescription drug plan is confusing and often leads to seniors paying hundreds of dollars more a year than they need to, a new study finds.

In an analysis of 2009 data from more than 412,000 Medicare beneficiaries, average age 75, researchers found that only 5.2 percent of the seniors chose the least expensive Medicare prescription drug benefit (Part D) plan that satisfied their medical needs. They overspent on Part D premiums and prescription drugs by an average of $368 a year.

The older the beneficiaries, the more likely they were to choose more expensive plans; for example, those over 85 overspent by $30 more than people aged 65 to 69. White people also tended to choose more expensive plans than blacks, Hispanics and Native Americans, the University of Pittsburgh Graduate School of Public Health researchers found.

Among those who were more likely to choose a less-expensive plan were seniors with common medical conditions, including diabetes and chronic heart failure. In addition, people with mental health disorders, such as Alzheimer's disease, spent an average of $10 less than those without such conditions, according to the report published in the October issue of the journal Health Affairs.

And having more options did not seem to help seniors choose the best plan for their needs. As the number of plans available in a region increased, the amount of overspending increased by $3.20 for each additional plan available, the study authors found.

"People need assistance in choosing the least expensive plan for their medical needs," lead author Chao Zhou, a post-doctoral associate at Pitt Public Health, said in a university news release. "Educational programs that help people navigate the dozens of plans available would make it easier to select plans that best meet their health care needs without overspending," Zhou added.

And study co-author Yuting Zhang, an associate professor of health economics at Pitt Public Health, suggested that the government could do more to help seniors. "In particular, government officials could recommend the three most appropriate Part D plans for each person, based on their medication history," Zhang said in the news release. "Alternatively, they could assign beneficiaries to the best plan for them based on their medication needs, while offering them the option to choose another plan instead."

More information

The U.S. Centers for Medicare and Medicaid Services has more about Medicare prescription drug coverage.