How HMOs structure primary care delivery.

To promote a shared understanding of how health maintenance organizations (HMOs) deliver primary care, the primary care staffing strategies of 23 HMOs are described: who they use as "gatekeepers," how they use nurse practitioners (NPs) and physician assistants (PAs), their referral policies, and their views on how the scope of practice of primary care may change. The study is based on on-site interviews with senior health plan personnel, and finds wide variations in primary care strategies, from open access to primary care and loose referral policies, to tight gatekeeping systems. In network/independent practice association (IPA) model plans, provider groups and IPAs, not the HMO, often determine who provides primary care. Implications are discussed.