Older patients who are treated by female doctors after being admitted to a hospital may be slightly less likely to die within a month of their admission than those who are treated by male doctors, according to a new study.

Researchers found that patients who were treated by female doctors had a 4 percent lower risk of dying within a month of being admitted to a hospital than those who were treated by male doctors. Moreover, these patients were 5 percent less likely to be readmitted to a hospital within a month, the researchers found.

More research is needed to understand why exactly patients treated by female doctors have lower mortality rate, study co-author Dr. Ashish Jha, a professor of health policy at Harvard T.H. Chan School of Public Health, said in a statement. [The Odds of Dying from Shark Attacks, Tsunamis & Dozens of Other Causes]

But previous research has suggested that there are differences between how male and female physicians practice medicine, Jha said. For example, studies have shown that female doctors may be more likely to adhere to clinical guidelines, provide preventive care and communicate with their patients more effectively than male ones, according to the study, published today (Dec. 19) in the journal JAMA Internal Medicine.

The new findings add to that research because Jha and his colleagues looked at actual patient outcomes. The results "suggest that those differences matter and are important to patient health," Jha said.

In the study, the researchers examined data on 1.5 million hospitalizations of more than 620,000 men and 960,000 women who were on Medicare and were admitted to U.S. hospitals for various conditions between 2011 and 2014. All of the patients were at least 65 years old, and their average age was 80, according to the study. During these hospitalizations, the patients in the study were treated by a total of about 60,000 doctors, including about 20,000 female doctors and about 40,000 male doctors.

The researchers looked at the relationship between the gender of the doctors who treated the patients and these patients' risk of death and needing to be hospitalized again within 30 days of their original admission.

The findings that the patients treated by female doctors were less likely to die or be hospitalized again are especially important in light of previous research that showed disparities between salary and promotion prospects of female and male doctors in academic medicine, said Dr. Anna Parks, a resident physician at the University of California, San Francisco, who co-authored an editorial accompanying the new study and published in the same journal. [Busted! 6 Gender Myths in the Bedroom & Beyond]

For example, one study showed that female physicians at academic centers earn an average of 8 percent less than male physicians at those centers, according to the editorial.

Some people have speculated that female academic physicians may be burdened by additional home responsibilities than their male colleagues, which supposedly may lead women to provide inferior care, Parks said.

"I think that this study is one piece of the puzzle to combat that claim," Parks told Live Science.

Originally published on Live Science.