What Was Measured?

The number of enrollees in commercial, MediCal, and Medicare HMO product lines offered by California’s largest HMOs. HMO membership by type of insurance is not ranked because it is not a quality measure.

Why Is It Important?

Enrollees may feel more comfortable in one HMO than another depending on the range of covered services, the perceived stability of the HMO, or the availability of different types of physicians who best meet their needs. The number of enrollees in an HMO’s commercial, MediCal, and Medicare product lines is one indication of how Californians select their HMO.

What Was the Source?

Data voluntarily reported by California HMOs to the National Committee for Quality Assurance (NCQA) and made available through NCQA’s Quality Compass®. The HMO Membership by Type of Insurance data comes from NCQA’s 2010 Quality Compass®, and is part of the same HMO data set used to generate the HEDIS and CAHPS quality information found in the health plan section of the 2011 OPA Report Card.

HMO Members by Type of Insurance

Aetna data for Medi-Cal and Medicare from 2009 reported directly to OPA

HMO Commercial

HMO Medi-Cal

HMO Medicare

Aetna Health of California, Inc. 422,907  Not reported 24,452 
Anthem Blue Cross - HMO 2,577,826  1,506,088  169,012 
Blue Shield of California - HMO 975,418  40,773 
CIGNA HMO 166,015 
Health Net of California, Inc. 836,611  829,771  131,462 
Kaiser Permanente - Northern California 2,494,298  73,434  398,810 
Kaiser Permanente - Southern California 2,619,381  82,597  357,940 
UnitedHealthcare of California (formerly PacifiCare) 724,215  326,781 
Western Health Advantage 67,808  13,224  1,209