The Medicare Part D prescription drug benefit is too confusing for seniors, often leading beneficiaries to choose unnecessarily expensive plans, according to a new study. What’s more, seniors may not even realize they’re overpaying.

Researchers at the University of Plymouth in the U.K. and at UCLA’s School of Public Health found that, regardless of age, seniors who had more plans to choose from were by far less likely to choose the most cost-effective plan. This group also had more difficulty answering questions about the plans. Researchers also noted that older adults are both less likely to choose the least-costly plan and more confident they have made the correct decision than younger adults. For the study, researchers randomly assigned more than 200 healthy adults, half over the age of 65, to choose from hypothetical Medicare Part D plans. One group had three plans to choose from, another group had 10 plans and another group could pick from 20 plans.

To remedy the situation and potentially stem some rising healthcare costs, researchers suggest either offering one choice seniors can opt in or out of (similar to Part A or Part B), standardizing the benefit, or simply reducing the number of plan options for seniors. Recently, the Department of Health and Human Services disclosed millions of dollars in inappropriate Medicare Part D payments to skilled nursing facilities, suggesting seniors aren’t the only ones confused by the benefit. (McKnight’s, 6/8) The Robert Woods Johnson Foundation funded the study.