> The researchers divided 500,000-plus cases into four categories: male doctors treating men; male doctors treating women; female doctors treating men; and female doctors treating women. “All of those are statistically indistinguishable except for male doctor–female patient,” says Brad Greenwood, an author on the study and a data scientist at the University of Minnesota. If a heart attack patient is a woman and her emergency physician is a man, he says, her risk of death suddenly rises by about 12 percent.