What Attitudes and Beliefs Underlie Patients ’ Decisions about Participating in

The theory of reasoned action, which postulates that personal attitudes and external social influences predict intentions to undertake a behavior, was used as a conceptual framework for developing a questionnaire to elicit beliefs and attitudes associated with the decision to participate in a hypothetical cancer chemotherapy trial. After completing the questionnaire, two-thirds of the 150 respondents indicated they would enroll in such a trial if it were available. Considerable variation existed in both "universal " and "trial-specific " beliefs and attitudes underpinning their intentions. A substantial amount of the variance in "intention " to participate was explained by "attitude " alone (75%). So-cial influences, although statistically significant, made a mere 1 % additional contribu-tion. One interpretation is that subjective expected-utility theory, which essentially pre-dicts beliefs or "attitude, " is a better model. The authors conclude that both theories may be criticized regarding how well they capture the rationality and nuances of de-cision behavior. Key words: attitudes; beliefs; clinical trials; oncology. (Med Decis Mak-ing 1998;18:61-69) The search for more effective therapies based upo