How disclosing HMO physician incentives affects trust. Further validation and reliability testing of the Trust in Physician Scale. The Stanford Trust Study Physicians.
Opinions are deeply divided over whether rewarding physicians for lowering costs decreases trust in physicians or insurers. To explore the effects of disclosing physician payment methods in HMOs, members of two similar HMO plans were randomized to intervention and control groups, and the experimental arm was told how the HMO paid their primary care physician. Separate disclosures were developed for each plan, one describing primarily capitation payment, and the other (mixed-incentive plan) describing fee-for-service payment with a bonus that rewards cost savings, satisfaction, and preventive services. The disclosures pointed out more of the positive than the negative features of these incentives. We found that the disclosures doubled the number of subjects with substantial knowledge of the physician incentives and halved the number with no knowledge. Nevertheless, the disclosures had no negative effects on trust of either physicians or insurers. The capitated plan disclosure had a small positive effect on trust of physicians. Disclosing the positive and negative features of incentives and increasing knowledge of these incentives does not, in the short term, reduce trust in physicians or insurers and may have a mild positive impact on physician trust, perhaps as a consequence of displaying candor and increasing understanding of positive features. To further validate and assess the reliability and validity of the Trust in Physician Scale.
                Consecutive adult patients (n = 414) from 20 community-based, primary care practices were enrolled in a prospective, 6-month study. At enrollment, subjects completed the 11-item Trust in Physician Scale plus measures of demographics, preferences for care, and satisfaction with care received from the physician. Continuity, satisfaction with care, and self-reported adherence to treatment were measured at 6 months. Reliability, construct validity, and predictive validity were assessed using correlation coefficients and analysis of variance techniques.
                The Trust in Physician Scale showed high internal consistency (Cronbach's alpha = .89) and good 1-month test-retest reliability (intraclass correlation coefficient = .77). As expected, trust increased with the length of the relationship and was higher among patients who actively chose their physician, who preferred more physician involvement, and who expected their physician to care for a larger proportion of their problems (P < 0.001 for all associations). Baseline trust predicted continuity with the physician, self-reported adherence to medication, and satisfaction at 6 months after adjustment for gender, age, education, length of the relationship, active choice of the physician, and preferences for care. After additional adjustment for baseline satisfaction with physician care, trust remained a significant predictor of continuity, adherence, and satisfaction.
                The Trust in Physician Scale has desirable psychometric characteristics and demonstrates construct and predictive validity. It appears to be related to, but still distinct from, patient satisfaction with the physician and, thus, provides a valuable additional measure for assessment of the quality of the patient-physician relationship.
Overall there remains insufficient evidence to conclude that any intervention may increase or decrease trust in doctors. Further trials are required to explore the impact of policy changes, guidelines and specific doctors' training on patients' trust.