Implicit bias among physicians and its prediction of thrombolysis decisions for black and white patients

Abstract

Context: Studies documenting racial/ethnic disparities in health care frequently implicate physicians' unconscious biases. No study to date has measured physicians' unconscious racial bias to test whether this predicts physicians' clinical decisions.

Objective: To test whether physicians show implicit race bias and whether the magnitude of such bias predicts thrombolysis recommendations for black and white patients with acute coronary syndromes.

Design, setting, and participants: An internet-based tool comprising a clinical vignette of a patient presenting to the emergency department with an acute coronary syndrome, followed by a questionnaire and three Implicit Association Tests (IATs). Study invitations were e-mailed to all internal medicine and emergency medicine residents at four academic medical centers in Atlanta and Boston; 287 completed the study, met inclusion criteria, and were randomized to either a black or white vignette patient.

Main outcome measures: IAT scores (normal continuous variable) measuring physicians' implicit race preference and perceptions of cooperativeness. Physicians' attribution of symptoms to coronary artery disease for vignette patients with randomly assigned race, and their decisions about thrombolysis. Assessment of physicians' explicit racial biases by questionnaire.

Results: Physicians reported no explicit preference for white versus black patients or differences in perceived cooperativeness. In contrast, IATs revealed implicit preference favoring white Americans (mean IAT score = 0.36, P < .001, one-sample t test) and implicit stereotypes of black Americans as less cooperative with medical procedures (mean IAT score 0.22, P < .001), and less cooperative generally (mean IAT score 0.30, P < .001). As physicians' prowhite implicit bias increased, so did their likelihood of treating white patients and not treating black patients with thrombolysis (P = .009).

Conclusions: This study represents the first evidence of unconscious (implicit) race bias among physicians, its dissociation from conscious (explicit) bias, and its predictive validity. Results suggest that physicians' unconscious biases may contribute to racial/ethnic disparities in use of medical procedures such as thrombolysis for myocardial infarction.

Figures

Figure 1

Implicit Association Test (IAT) sample screens and stimuli. This figure displays sample screens and stimuli from the race preference (black-white/good-bad) IAT. Sample screens a, b, c, and d represent examples of pairing tasks that participants rapidly complete. Pictures of black or white individuals and words representing good or bad evaluative attributes are flashed in the center of the screen, and subjects quickly classify these as to whether they belong with category pairs shown in the upper left or the upper right of their screens using the e or i key on their computer keyboard. Numerous pictures and words are flashed onscreen for each of the two possible pairings, with responses usually taking less than a second and the order counterbalanced across participants. The speed to associate black+bad and white+good (screens a and b) relative to the opposite pairing of black+good and white+bad (screens c and d) constitutes the IAT score, interpreted to be a measure of implicit race preference

Figure 2

Magnitude of physicians’ explicit (self-reported) and implicit (Implicit Association Test) race bias on a standardized scale—Cohen’s effect size d

Figure 3

Relationship between physician race preference Implicit Association Test (IAT) score and thrombolysis decisions by patient race. *P < .05, **P = .05–0.11, B values are standardized regression coefficients that describe the magnitude of each relationship that the regression lines represent. IAT bias is a continuous variable represented on the polar ends of the x-axis as low antiblack IAT and high antiblack IAT. Treatment recommendation of thrombolysis is represented on the y-axis and is a dichotomous variable for which 0 means “would not give thrombolysis” and 1 means “would give thrombolysis.” Subpanels A–D represent race preference, general cooperativeness, medical cooperativeness, and the composite IAT measures, respectively

Figure 4

Relation between physicians’ awareness of the study’s purpose and Implicit Association Test (IAT) bias on recommendation for thrombolysis (black patients only). B values are standardized regression coefficients that describe the magnitude of each relationship that the regression lines represent (P = .001). IAT bias is a continuous variable represented on the polar ends of the x-axis as low antiblack IAT and high antiblack IAT. Treatment recommendation of thrombolysis is represented on the y-axis and is a dichotomous variable for which 1 means “no recommendation” was given and 2 means a “recommendation” was given