Four Dayton hospitals are among the top 5 percent in the nation for emergency medicine, according to a new study.

The study, released Tuesday by HealthGrades — an independent source of physician information and hospital quality ratings — also found Dayton to be the fourth best city in the U.S. for emergency medicine. Cincinnati was ranked No. 1.

The top Dayton hospitals for emergency medicine are:

• Good Samaritan Hospital ;

• Grandview Medical Center ;

• Kettering Medical Center ; and

• Miami Valley Hospital

The findings are based on an analysis of more than seven million Medicare patient records from 2007 to 2009. The study focused on 12 of the most common and life-threatening medical emergencies among that patient population, including heart attack, stroke, pneumonia and chronic obstructive pulmonary disease.The study recognized the top 10 cities for emergency medicine based on overall mortality rate for patients admitted through the emergency department.

Hospital ERs in the cities also were rated for observed-to-expected ratio, where less than 1.0 indicates better than expected performance.Other key findings of the study include:• Medicare patients treated at hospitals recognized in the top five percent in the nation had a 40 percent lower risk of death compared to patients treated at other hospitals.

To be included in the analysis, hospitals must have met minimum thresholds in terms of patient volumes, quality ratings and the range of services provided. Individuals may compare their local hospitals online at HealthGrades.com. HealthGrades’ hospital ratings are independently created; no hospital can opt-in or opt-out of being rated, and no hospital pays to be rated.