With an annual death toll of about 440,000, preventable hospital errors now rank as the third leading cause of death in the U.S., a Leapfrog Group report stated. The Leapfrog Group is an independent nonprofit group whose mission is to promote patient safety.

The group released a fall 2013 update its Hospital Safety Score, which grades more than 2,500 U.S. hospitals. The report found that while hospitals are improving in their efforts to prevent errors, accidents, injuries and infections that harm or kill patients, they can still do better.

Of the hospitals the group graded, 814 earned an A, 661 earned a B, 893 earned a C, 150 earned a D and 22 earned an F. The majority of hospitals did not show much improvement in terms of safety, but 3.5 percent jumped two or more grade levels.

The state with the highest number of grade A hospitals was Maine. On the other hand, New Hampshire, Arkansas, Nebraska and New Mexico had the fewest grade A hospitals. In addition, all hospitals in the Kaiser Permanente and Sentara Healthcare systems earned A grades.

The latest Hospital Safety Score report includes two additional safety measures: catheter-associated urinary tract infections and surgical site infections: colon, which the group said are among the most common nosocomial infections.

The score report is available online for free and is also available through a mobile app.