California HMOs may provide national forecast.

With more than one quarter of the nation's health maintenance organization (HMO)-insured patients, California may provide an example of what other states can expect in terms of the financial viability of HMOs. A recent study of the enrollment patterns, premium trends, and net profit margins of 47 full-service California HMO plans over a four-year period showed that larger HMOs tend to be in better financial health than smaller HMOs. Meanwhile, the state has revised its code of regulations to include stricter requirements for the operation of full-service HMO plans.