At a time when the cost of many prescription drugs is soaring, Medicare Part D helps beneficiaries pay for needed medications through private insurance plans that receive premiums from both enrollees and the government. Approximately 39 million beneficiaries receive Part D benefits through more than 2,000 plans sponsored by private companies, and payments for Part D drugs are approximately $121 billion per year.

As with any large, fast-growing government program, the possibility of fraud is always a concern.

"The Centers for Medicare & Medicaid Services relies on plan sponsors to be the first line of defense against fraud, waste and abuse in Part D," according to the U.S. Department of Health and Human Services' Office of Inspector General. "Plan sponsors are responsible for paying claims, monitoring billing patterns and establishing compliance plans that specify their procedures for preventing and detecting fraud, waste and abuse. Plan sponsors must also ensure that entities with which they subcontract meet regulatory and compliance requirements."