Diagnostic certainty as a source of medical practice variation in coronary heart disease: results from a cross-national experiment of clinical decision making

Abstract

The authors examined physician diagnostic certainty as one reason for cross-national medical practice variation. Data are from a factorial experiment conducted in the United States, the United Kingdom, and Germany, estimating 384 generalist physicians' diagnostic and treatment decisions for videotaped vignettes of actor patients depicting a presentation consistent with coronary heart disease (CHD). Despite identical vignette presentations, the authors observed significant differences across health care systems, with US physicians being the most certain and German physicians the least certain (P < 0.0001). Physicians were least certain of a CHD diagnoses when patients were younger and female (P < 0.0086), and there was additional variation by health care system (as represented by country) depending on patient age (P < 0.0100) and race (P < 0.0021). Certainty was positively correlated with several clinical actions, including test ordering, prescriptions, referrals to specialists, and time to follow-up.

Figure 1

Physicians’ certainty of coronary heart disease (CHD) diagnoses in 3 countries (P < .0001). Certainty ranges from 0 (complete uncertainty) to 100 (complete certainty). The box and whiskers plot can be interpreted as follows: the whiskers extend to the data minimum and maximum, the bottom of the box is at the 25th percentile, the top of the box is at the 75th percentile, the middle line is the median, and the + is at the mean.

Figure 2

Figure 2a. Two-way interaction effect of patient race and physician level of experience on physicians’ diagnostic certainty for coronary heart disease (CHD), 0 to 100 (United States and United Kingdom only; P = 0.0500). Figure 2b. Two-way interaction effect of patient age and patient gender on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0086). Figure 2c. Two-way interaction effect of patient age and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0100). Figure 2d. Two-way interaction effect of patient race and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0021).

Figure 2

Figure 2a. Two-way interaction effect of patient race and physician level of experience on physicians’ diagnostic certainty for coronary heart disease (CHD), 0 to 100 (United States and United Kingdom only; P = 0.0500). Figure 2b. Two-way interaction effect of patient age and patient gender on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0086). Figure 2c. Two-way interaction effect of patient age and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0100). Figure 2d. Two-way interaction effect of patient race and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0021).

Figure 2

Figure 2a. Two-way interaction effect of patient race and physician level of experience on physicians’ diagnostic certainty for coronary heart disease (CHD), 0 to 100 (United States and United Kingdom only; P = 0.0500). Figure 2b. Two-way interaction effect of patient age and patient gender on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0086). Figure 2c. Two-way interaction effect of patient age and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0100). Figure 2d. Two-way interaction effect of patient race and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0021).

Figure 2

Figure 2a. Two-way interaction effect of patient race and physician level of experience on physicians’ diagnostic certainty for coronary heart disease (CHD), 0 to 100 (United States and United Kingdom only; P = 0.0500). Figure 2b. Two-way interaction effect of patient age and patient gender on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0086). Figure 2c. Two-way interaction effect of patient age and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0100). Figure 2d. Two-way interaction effect of patient race and country on physicians’ diagnostic certainty for CHD, 0 to 100 (P = 0.0021).