The determinants of physician attitudes and subjective norms toward drug information sources: Modification and test of the theory of reasoned action

Purpose. To improve upon the theory of reasoned action and apply it to pharmaceutical research, we investigated the effects of relevant appraisals, attributes, and past behavior of physicians on the use of drug information sources. We also examined the moderating effects of practice characteristics. Methods. A mail questionnaire asked HMO physicians to evaluate seven common sources of drug information on general appraisals (degree of usefulness and ease of use), specific attributes (availability, quality of information on harmful effects and on drug efficacy), and past behavior when searching for information on a new, simulated H₂ antagonist agent. Semantic differential scales were used to measure each appraisal, attribute and past behavior. Information was also collected on practice characteristics. Results. Findings from 108/200 respondents indicated that appraisals and attributes were useful determinants of attitudes and subjective norms toward use. Degree of usefulness and quality of information on harmful effects were important predictors of attitudes toward use for several sources of information. Ease of use and degree of usefulness were important predictors of subjective norms toward use. In many cases, moderating effects of practice characteristics were in opposing directions. Past behavior had significant direct effects on attitudes toward the PDR. Conclusions. The findings suggest ways to improve the usefulness of the theory of reasoned action as a model of decision-making. We also propose practical guidelines that can be used to improve the types of drug information sources used by physicians.