Fitness memberships and favorable selection in Medicare Advantage plans.

Background: Because Medicare Advantage plans must pay for covered services, they may design insurance benefits to appeal to healthier beneficiaries.

Methods: We identified 11 Medicare Advantage plans that offered new fitness-membership benefits in 2004 or 2005 and matched these plans to 11 Medicare Advantage control plans that did not offer coverage for fitness memberships. Using a difference-in-differences approach, we compared the self-reported health status of persons who enrolled after the fitness benefit was added to the plan with the self-reported health status of persons entering the same plan before the fitness benefit was offered.

Results: The proportion of enrollees reporting excellent or very good health was 6.1 percentage points higher (95% confidence interval [CI], 2.6 to 9.7) among the 755 new enrollees in plans that added fitness benefits than among the 4097 earlier enrollees. The proportion of new enrollees reporting activity limitation was 10.4 percentage points lower (95% CI, 6.6 to 14.3) and the proportion reporting difficulty walking was 8.1 percentage points lower (95% CI, 4.4 to 11.7), as compared with earlier enrollees. Within control plans, the differences between the 1154 new enrollees and the 3910 earlier enrollees were 1.5 percentage points or less for each measure. The adjusted differences between the fitness-benefit plans and the control plans were 4.7 percentage points higher for general health (95% CI, 0.2 to 9.2), 9.2 percentage points lower for activity limitation (95% CI, 5.1 to 13.3), and 7.4 percentage points lower for difficulty walking (95% CI, 4.5 to 10.4). These differences persisted at 2 years for activity limitation and difficulty walking.

Conclusions: Medicare Advantage plans offering coverage for fitness memberships may attract and retain a healthier subgroup of the Medicare population. (Funded by the National Institute on Aging.).