Kaiser Permanente hospitals in Santa Rosa and Vallejo were among 15 other Kaiser hospitals to receive an "A" grade on the Hospital Safety Score by The Leapfrog Group, an independent national nonprofit run by employers and other large purchasers of health benefits.

Kaiser's medical center in San Rafael was among three other Kaiser hospitals to receive a "B" grade, the next highest ranking.

"Our excellent ratings from Leapfrog and other third-party organizations reflect the superiority of our integrated model for medical care, which enables our medical group, hospitals and health plan to work together on behalf of our patients to achieve the highest quality outcomes," said Dr. Robert Pearl, executive director and chief executive officer of The Permanente Medical Group, in a statement.

The scores were calculated under the guidance of the The Leapfrog Group's blue ribbon expert panel using publicly available data on patient injuries, medical and medication errors, and infections. Hospitals were assigned letter grades -- A through F -- for safety.

Other Kaiser hospitals in Northern California with "A" scores were Antioch, Fremont, Hayward, Manteca, Oakland, Redwood City, Roseville, Sacramento, San Jose, San Francisco, Santa Clara, South Sacramento and South San Francisco.

The Hospital Safety Score website (www.hospitalsafetyscore.org) also has information on how the public can protect themselves and loved ones during a hospital stay.