December 8 of this year will mark the 10-year anniversary of enactment of the Medicare Modernization Act (MMA), a law that greatly improved healthcare coverage for seniors in this country. Included in this landmark legislation was the creation of the Medicare prescription drug benefit program, also known as Medicare Part D. This program has been a tremendous success by making life-saving medications available and affordable for the millions of beneficiaries who rely on them.

However, as part of the broader budget debate in which Congress is currently engaged, multiple proposals exist that would dramatically change the makeup of the program – essentially gutting effective pricing structures and other elements that have, since the program’s implementation in 2006, made Part D a great value for beneficiaries and taxpayers. Evidence of the success of Part D is seen through a satisfaction survey released last week by the Healthcare Leadership Coalition’s Medicare Today initiative.

This year – the eighth year we have commissioned this annual survey – is certainly no exception. 90 percent of seniors are satisfied with their Medicare prescription benefit coverage. In addition, 95 percent of the beneficiaries surveyed say their Part D plan is convenient to use and 84 percent say both their premiums and co-pays are affordable. Even more impressive are the satisfaction rates of major demographic groups surveyed – 95 percent of African Americans and 94 percent of Hispanics are satisfied with Part D.

These are astonishing numbers and consistent with other satisfaction surveys released this year and in previous years. So, it begs the question, why do some legislators want to tamper with one of the most successful government programs in the history of this country?

Supporters of overhauling the program will argue it ultimately comes down to cutting costs, even though expenditures for the Part D program in 2013 will represent only a fraction of the overall Medicare budget. In addition, a recent MedPAC analysis found that average prices for prescribed medications purchased through Part D, including generics, only increased by two percent during the program’s first five years. It’s no wonder that average monthly Part D premiums will be about $31 in 2014, the fourth straight year premiums have stayed at a stable level.

In addition, Medicare Part D, according to the Congressional Budget Office is costing taxpayers 46 percent less, over the past decade, than what was projected when the program was launched. How many government programs can we identify that are this successful, cost-effective and under budget?

However, as with any and all government programs, there is always room for improvement.  Of course, there are incremental steps we can – and should – take to ensure this program is adapting to the needs of this country’s senior population and the healthcare challenges they face. Let's be clear, though, that the system works, and it works incredibly well at a level of efficiency and cost containment that we wish all government programs could achieve.

The cliché of “If it isn’t broken, don’t fix it,” may be considered trite, but I simply cannot think of a better case study in the history of this country than the success of the Medicare Part D program. Proposals to drastically overhaul this essential program for seniors will inevitably undermine the ability of Medicare Part D to continue providing affordable medications to the nation's seniors and beneficiaries with disabilities. As Congress debates larger budgetary issues, it should consider Part D's fiscal successes as well as its overwhelming popularity with the millions of Americans it serves.

Grealy is president of the Healthcare Leadership Council, a coalition of chief executives of the nation’s leading healthcare companies and organizations.