The number of people who enter the Coverage Gap or Doughnut Hole portion of their Medicare prescription drug plan changes each year based on several different things including:
- The total number of people eligible for a Medicare prescription drug plan,
- The type of prescription drug plans available (For instance, is there a drug plan this year that provides complete doughnut hole coverage?), and
- The general Medicare population's drug usage (Are people moving to generics or staying healthier?).
In 2006, the Centers for Medicare and Medicaid Services (CMS) estimated that about 6% of Medicare prescription drug plan enrollees or 1.5 Million Medicare beneficiaries entered the Doughnut Hole portion of their drug plans. The number of people entering the 2006 Doughnut Hole was perhaps lower then expected because many people were not enrolled in their Part D plans for a full year.
The Actuarial Research Corporation (in an analysis for the Kaiser Family Foundation) estimated that over 3.4 Million people or 14% of all Part D enrollees entered the Doughnut Hole in 2007.