A single mathematical model predicts physicians' recommendations and postmenopausal women's decisions to participate in a clinical trial to prevent breast cancer or coronary heart disease.

Abstract

Few eligible postmenopausal women participate in clinical trial research to prevent breast cancer or coronary heart disease, making it impossible to adequately assess the efficacy of tested interventions for this vulnerable group. To elucidate the causal factors and decision model underlying participation behavior, 180 white, African American, and Hispanic postmenopausal women judged their likelihood of participation in a breast cancer or coronary heart disease prevention clinical trial in scenarios with varied cost/remuneration, perceived risk, doctor's recommendation, and expected toxicity. In addition, 293 white, African American, and Hispanic male and female physicians judged the strength of their participation recommendation in scenarios with varied cost/remuneration, expected toxicity, patient's age, and the source of the information about the clinical trial. An additive and constant-weight-averaging model were rejected. The same configural-weight-range model accounted for judgments in both breast cancer and coronary heart disease scenarios, with different parameter values for each group. According to this model, white and Hispanic women under 70 years of age are most likely to participate, even under somewhat adverse conditions; costs and high toxicity levels act as severe barriers to physicians' positive recommendations and women's participation. Perceived risk was the most important factor for women, yet only 8% and 15% reported ever having received risk information from their doctor for breast cancer and coronary heart disease, respectively. For these two diseases, respectively, 75% and 48% of women rated their risk of the disease as low and 76% and 88% reported they had never heard of a randomized clinical trial or of a prevention clinical trial being conducted. These results have implications for education, information dissemination, and prevention clinical-trial planners.