A new study by the California Nurses Association/National Nurses United (CNA/NNU) finds that California’s largest private insurance companies continue to deny more than one-fourth of all claims and two firms rejected about 40 percent of submitted claims.

CNA/NNU Co-President DeAnn McEwen says the rejection rates show one reason why:

medical bills are a prime source of personal bankruptcies as doctors and hospitals will push patients and their families to make up what the insurer denies.

For the first three quarters of 2010, seven California insurance giants rejected 13.1 million claims—26 percent of all claims submitted—a number only slightly below the 26.8 percent rate for 2009. The data, new findings by the Institute for Health and Socio-Economic Policy, the CNA/NNU research arm, is based on data from the California Department of Managed Health Care.

Claims denial rates by leading California insurers, first three quarters, 2010:

• PacifiCare—43.9 percent
• Cigna—39.6 percent
• Anthem Blue Cross—27.3 percent
• HealthNet—24.1 percent
• Blue Shield—21.9 percent
• Kaiser Permanente—20.2 percent
• Aetna—5.9 percent

Tomorrow, nurses, patients and consumer advocates will cite this data, along with the widely criticized pricing practices of Blue Shield—the company recently announced  rate hike of up to 59 percent for individuals—and other insurers, at a protest Tuesday at the San Francisco headquarters of Blue Shield.