The University of California Los Angeles (UCLA) Center for Health Policy Research released a study examining 2007 data on Californians’ health status and service utilization.  The study examines trends and characteristics among different types of health plans, finding an increasing reliance upon high-deductible health plans (HDHP). 

From the executive summary:

Health maintenance organizations (HMOs) serve as insurers and providers of health care to 21% of the U.S. population, according to the Kaiser Family Foundation. HMOs have higher rates of penetration in California than in any other state. Although the majority of HMO enrollees have either employer-based or individually purchased coverage, HMOs also provide care through California’s Medicaid program (Medi-Cal) for low-income families, as well as through the federal Medicare program for individuals ages 65 and over.

Full Report: Profiling California’s Health Plan Enrollees: Findings from the 2007 California Health Interview Surve (PDF | 632KB)  

UCLA Center for Health Policy Research. (2010). Profiling California’s health plan enrollees: findings from the 2007 California health interview survey. Roby, D., Nicholson, G., Kominski, G.