Types of services include - among others - physician services, durable medical equipment, laboratory' tests, and outpatient hospital services. Each expenditure category is projected on the basis of recent past trends in growth per enrolee, along with applicable legislated limits on payment updates. To project future SMI part D21 costs, historical per capita spending for beneficiaries in private prescription dmg plans, low'-income beneficiaries, and beneficiaries in employer-sponsored retiree health plans is used as a projection base.