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Purpose: Patients’ expectations of benefit from phase I trials often far exceed their physicians’ estimates. We hypothesized that patient-physician differences are related more to differences in the way patients and physicians use the quantitative response scale than to differences in each person’s underlying qualitative sense of the relative likelihoods of various treatment outcomes.
Methods: Adult cancer patients considering participation in phase I trials, along with their physicians, completed surveys before initiating therapy. Patients and their physicians rated the likelihood (0% to 100%) of benefit and harm from experimental and standard therapies, yielding a profile of 4 likelihood ratings for each person. We assessed each patient-physician pair’s differences in use of the response scale by examining differences in the mean of each person’s ratings (“level”) and differences in the standard deviation of each person’s ratings (“scatter”). In addition, we characterized the relative “ups and downs” of the ratings in each subject’s profile as the “shape” of that profile. We assessed patient-physician differences in the qualitative sense of the relative likelihoods of treatment outcomes by correlating the shape of each patient’s profile with the shape of the physician’s profile. We then correlated discrepancies in expectation of benefit from experimental therapy with differences in level, scatter, and shape.
Results: On average, patients’ profiles were 28.46 points higher in level and displayed greater scatter (difference in SD, 15.15) than their physicians’ profiles. The average correlation between the shapes of patients’ and physicians’ profiles was 0.03, reflecting poor agreement in the qualitative sense of the likelihoods of the 4 treatment outcomes. Disagreement in the likelihood of benefit from experimental therapy was associated with disagreement in level (r=0.68; 95% CI, 0.56 to 0.80) and scatter (r=0.45; 95% CI, 0.32 to 0.59) but not shape (r=0.02; 95% CI, -0.09 to 0.13).
Conclusions: The magnitude of discrepancy between patients and physicians in expectation of benefit from experimental therapy was related to the way subjects used the response scale but was unrelated to how well patients and physicians agreed in their qualitative sense of the relative likelihood of each treatment outcome. If treatment decisions are made on the basis of this qualitative sense, patients and physicians might disagree substantially about chance of benefit from experimental therapy yet still arrive at the same decision.
See more of Poster Session - Utility Theory; Health Economics; Patient & Physician Preferences; Simulation; Technology Assessment
See more of The 26th Annual Meeting of the Society for Medical Decision Making (October 17-20, 2004)