Objective: To explore an approach to measuring the quality of decisions made in the treatment of early stage breast cancer, focusing on patients' decision-specific knowledge and the concordance between patients' stated preferences for treatment outcomes and treatment received.
Methods: Candidate knowledge and value items were identified after an extensive review of the published literature as well as reports on 27 focus groups and 46 individual interviews with breast cancer survivors. Items were subjected to cognitive interviews with six additional patients. A preliminary decision quality measure consisting of five knowledge items and four value items was pilot tested with 35 breast cancer survivors who also completed the control preferences scale and the decisional conflict scale (DCS).
Results: Preference for control and knowledge did not vary by treatment. The mean of the participants' knowledge scores was 54%. There was no correlation between the knowledge scores and the informed subscale of the DCS (Pearson r = .152, n = 32, p = 0.408). Patients who preferred to keep their breast were over five times as likely to have breast-conserving surgery than those who did not (OR 5.33, 95% CI (1.2, 24.5), p = 0.06). Patients who wanted to avoid radiation were six times as likely to choose mastectomy than those who did not (OR 6.4, 95% CI (1.34, 30.61), p = 0.04).
Conclusion: Measuring decision quality by assessing patients' decision-specific knowledge and concordance between their values and treatment received, is feasible and important. Further work is necessary to overcome the methodological challenges identified in this pilot work.
Practice implications: Guidelines for early stage breast cancer emphasize the importance of including patients' preferences in decisions about treatment. The ability of doctors and patients to make decisions that reflect the considered preferences of well-informed patients can and should be measured.