Wellness incentives, equity, and the 5 groups problem.

Wellness incentives are an increasingly popular means of encouraging participation in prevention programs, but they may not benefit all groups equally. To assist those planning, conducting, and evaluating incentive programs, I describe the impact of incentives on 5 groups: the "lucky ones," the "yes-I-can" group, the "I'll-do-it-tomorrow" group, the "unlucky ones," and the "leave-me-alone" group. The 5 groups problem concerns the question of when disparities in the capacity to use incentive programs constitute unfairness and how policymakers ought to respond. I outline 4 policy options: to continue to offer incentives universally, to offer them universally but with modifications, to offer targeted rather than universal programs, and to abandon incentive programs altogether.