By Shankar Vedantam
Monday, August 13, 2007
Long before word recently broke that white referees in the National Basketball Association were calling fouls at a higher rate on black athletes than on white athletes, and long before studies found racial disparities in how black and white applicants get called for job interviews, researchers noted differences in the most troubling domain of all -- disparities in survival and health among people belonging to different racial groups.
Black babies, according to the federal government's Centers for Disease Control and Prevention, have higher death rates than white babies. Black women are more than twice as likely as white women to die of cervical cancer. And in 2000, the death rate from heart disease was 29 percent higher among African Americans than among white adults, and the death rate from stroke was 40 percent higher.
The trouble with all these numbers, as with the NBA study -- which was conducted by researchers Justin Wolfers and Joseph Price -- is that they do not explain why such differences exist among racial groups.
Some studies have shown, similar to the NBA analysis, that diagnoses and treatments offered by physicians vary between racial groups, for diseases as dissimilar as heart disease and schizophrenia. But does this reflect physician bias, or the possibility that patients from different backgrounds present themselves differently? Could race be a marker for some other variable that really matters, such as health insurance status?
A new study by researchers at Massachusetts General Hospital and other institutions affiliated with Harvard University provides empirical evidence for the first time that when it comes to heart disease, bias is the central problem -- bias so deeply internalized that people are sincerely unaware that they hold it.
Physicians who were more racially biased were less likely to prescribe aggressive heart-attack treatment for black patients than for whites. The study was recently published in the Journal of General Internal Medicine.
The research finding cannot be automatically extrapolated to the NBA or other domains, but it does suggest a mechanism by which disparities emerge. No conscious bias was apparently present -- there was no connection between the explicit racial views of physicians and disparities in their diagnoses. It was only when researchers studied physicians' implicit attitudes -- by measuring how quickly they made positive or negative mental associations with blacks and whites -- that they found a mechanism to explain differences in medical judgment.
"Physicians who had higher biases against blacks were less likely to recommend thrombolysis for blacks," said Alexander R. Green, the study's chief investigator and a faculty member at the Disparities Solutions Center at Massachusetts General Hospital.
Thrombolysis is a clot-busting technique given when doctors suspect that a patient is having a heart attack. It is not to be given lightly, which is why a physician's judgment is crucial in telling patients who are merely having aches and pains apart from patients at death's door.
Green had 287 physicians at four academic medical centers in Boston and Atlanta take a psychological test for bias. He followed it up by providing a case study of a 50-year-old man called "Mr. Thompson," a smoker with a history of hypertension, "who presents to the emergency department with chest pain. He appears to be in a lot of pain describing it as 'sharp, like being stabbed with a knife.' "
The patient was described to some physicians as white and to others as black. Physicians were asked to decide whether the pain was the result of coronary artery disease and whether to prescribe clot-busting drugs.
Doctors were more likely to think "Mr. Thompson" was having a heart attack when he was black than when he was white. But they did not prescribe treatment to reflect this -- physicians who thought a black Mr. Thompson was having a heart attack prescribed thrombolysis less often than when they thought a white Mr. Thompson was having one.
Green said numerous other studies are underway to evaluate the utility of psychological tests for bias to explain disparities in medical domains. "We have reason to suspect you can measure unconscious bias among physicians and show it has an impact on treatment decisions," he said.
Mahzarin Banaji, a co-author and Harvard psychologist who helped develop the Implicit Association Test used in this study, said the racial bias unearthed by the study is at odds with conventional views of bigotry -- and perhaps more insidious. Rather than harboring deliberate ill will, she said, the physicians had apparently internalized racial stereotypes, and these attitudes subtly influenced their medical judgment without their even realizing it.
The study of physicians had one hopeful note, Banaji said: Doctors at least were willing to open their subconscious minds for inspection, which is something that many other professionals -- judges, police officers and NBA referees -- rarely are willing to do.