Inasmuch as 1 in 4 doctors in the United States were born abroad, a study published last month could not be more politically charged. It came when President Trump’s 90-day ban on people from seven Muslim countries entering the U.S. took effect. (The courts have nullified the ban as of this writing.) The study, published in BMJ, found that older Medicare patients treated by doctors educated at medical schools outside the U.S. are a bit less likely to die within 30 days than those patients treated by U.S. educated doctors, according to STAT.

STAT reported that physicians who graduated from U.S. colleges but went to medical schools in the Caribbean or Central America were excluded. Study coauthor Yusuke Tsugawa, MD, who graduated from a medical school in Japan, told STAT that those graduates “are known to be less qualified and would have biased our analysis.”

BMJ says that the timing of the study was coincidental; researchers began the project a year ago and the study publication date had been locked in before Trump’s announcement.

The political implications were unavoidable. Ashish Jha, MD, of Harvard T.H. Chan School of Public Health, told STAT that the study underscores that America “attracts the very best and the very brightest. Certainly that’s true in science, and our paper says that’s true in medicine as well.”

He added that Trump’s action “sends a signal that America is not going to be as open anymore…. The ones who will lose will be American patients.”

The patients’ average age was 80 with the most common causes of death being congestive heart failure, sepsis, COPD, and pneumonia. Data came from 1.2 million hospital admissions of Medicare patients, ages 65 and older. The information was collected between 2011 and 2014 and included 44,227 internists.

The difference between doctors educated abroad and those educated in the U.S. amounts to “at most a modest clinical significance,” the study states. The difference in patient mortality was an adjusted odds ratio of 0.95.

The study states that 11.2% of Medicare patients cared for by foreign-born doctors died within 30 days of discharge. For U.S. educated doctors, it was 11.6%.

“Based on the risk difference of 0.4 percentage points, for every 250 patients treated by U.S. medical graduates, one patient’s life would be saved if the quality of care were equivalent between the international graduates and U.S. graduates,” the study states.