In recent years, researchers and policy makers have increasingly focused their attention on the variation in clinical practice patterns across geographic areas and practice settings. Wennberg and Gittelsohn1-3 have identified wide variations across small geographic areas in the use of selected surgical procedures. Numerous studies of Health Maintenance Organizations (HMOs) indicate substantially lower hospitalization rates for enrollees in prepaid group practices than for enrollees with conventional insurance coverage.4 Such studies gain more than academic interest as insurers and the government seek ways to contain medical care expenditures by choosing selected providers and medical care systems or by developing incentives for physicians to change their practice patterns.
See also p 1886.
While the evidence is convincing that differences exist in practice patterns, the reasons for the observed differences are not well understood and there is much more rhetoric than research. Some argue that the prepayment arrangements in HMOs encourage