Both the University of Michigan Health System and St. Joseph Mercy Ann Arbor have been graded with an “A” for patient safety in their hospitals, according to a new report released this week.

The Leapfrog Group, an independent national nonprofit run by employers and health benefit purchasers, released Hospital Safety Scores for facilities across the country.

Every day in hospitals across the country, more than 400 people die because of a preventable hospital error, according to the report’s website.

The report used 26 measures of publicly available hospital safety data to generate the grades, which evaluate a hospital’s ability to keep patients safe from infections, and injuries, as well as medical and medication errors.

Of 2,652 general hospitals issued a score, UMHS and St. Joseph Ann Arbor are among 32 facilities in Michigan and 729 in the nation to earn an “A."

“It’s a new day for patients and families who want to choose the best place for their care based on hard numbers and performance. While we’re grateful that our efforts have earned this grade, we’ll continue to push ourselves to do even better," said UMHS Chief Medical Officer Dr. Darrell Campbell, Jr.

Within the St. Joseph Mercy Health System, hospitals in Ann Arbor, Chelsea, Livingston, Oakland and Livonia all received A grades. Its hospital in Port Huron received a B.

“The Hospital Safety Score reflects our unrelenting focus on teamwork in defining and implementing health care processes that make care safer and optimize patient outcomes. Patient safety is the foundation of all of our care improvement activities,” said Dr. Lakshmi Halasyamani, chief medical officer at St. Joseph Mercy Ann Arbor and Livingston, in a news release.

Amy Biolchini covers Washtenaw County, health and environmental issues for AnnArbor.com. Reach her at (734) 623-2552, amybiolchini@annarbor.com or on Twitter.