displays the recruitment status based on the 2840 letters that were sent to patients. Follow-up phone contact, initiated by either the patients or research staff, was made for 1545 of the patients to reach the goal of 500 patient interviews. Of the patients we phoned, 510 agreed and completed interviews, whereas 862 decliners or passive decliners (ie, did not return 4 phone calls). After we excluded the 40 patients who participated in the pilot phase of the study, 470 surveys were available for the analysis. shows the characteristics of the patients by disclosure group. None of the participant characteristics differed by experimental group (P > .19 for all comparisons). Most participants were white men with relatively high education levels and incomes. One third of the participants had previously participated in a research study, half of whom had participated in a cardiology trial.
Effects of disclosure on willingness to participate
displays the mean responses by experimental group for each of the outcomes. Although patients in all 3 disclosure groups expressed a moderate willingness to participate in the hypothetical clinical trial, there were significant differences across groups (P = .02). Patients in the equity group reported less willingness to participate (mean, 3.20; SD, 1.32) than patients in the per capita payments group (mean, 3.51; SD, 1.30; P = .01) and the no disclosure group (mean, 3.50; SD, 1.29; P = .03). This difference corresponded to an effect size of 0.23 standard deviations. Patients with higher Trust in Medical Research scores (measured at baseline) expressed greater willingness to enroll in the hypothetical clinical trial (semipartial r = 0.22; P < .001).
Responses by Experimental Group and Relationship With Trust in Medical Research
Participants placed less importance on the possibility of financial benefit to the investigator than on other factors (). Patients in the equity group rated the possibility of financial benefit as more important (mean, 2.65; SD, 1.59) than did patients in the per capita payments group (mean, 1.97; SD, 1.24; P < .001), corresponding to a difference of 0.49 SDs. Helping others was rated as somewhat more important in the per capita payments group (mean, 4.14; SD, 0.95) than in the no disclosure group (mean, 3.87; SD, 1.01; P = .01), corresponding to a difference of 0.28 SDs. No other importance factors differed by disclosure group. The only importance factor related to the Trust in Medical Research score was the importance of helping others (semipartial r = 0.18; P < .001).
Effects of disclosure on trust
Trust in the hypothetical investigator was moderately high among all 3 disclosure groups and differed by group. Level of trust in the investigator was highest in the per capita payments group (mean, 3.88; SD, 0.82) and lowest in the equity group (mean, 3.60; SD, 1.01; P < .001), corresponding to a difference of 0.30 SDs. Trust in the investigator was also greater in the no disclosure group (mean, 3.77; SD, 0.82) than in the equity group (P = .04; difference, 0.18 SDs), but did not differ significantly from the per capita payments group (P = .15, difference, 0.13 SDs). Higher Trust in Medical Research scores (measured at baseline) were associated with greater trust in the investigator at the time of consent (semipartial r = 0.38; P < .001).
Trust in the hypothetical sponsor and research institution did not differ by disclosure group. However, Trust in Medical Research scores were positively associated with both trust in the sponsor (semipartial r = 0.35; P < .001) and trust in the research institution (semipartial r = 0.37; P < .001). As shown in , trust was highest for the research institution, next highest for the investigator, and lowest for the research sponsor (P < .001). (There was a significant interaction between object of trust and disclosure group [P = .04], but the main effect for object of trust remained significant for each disclosure group.)
Participants' comments about financial interests
shows the distribution of participants' comments about the hypothetical investigator's financial interests. Few patients (less than 3%) had positive comments, and these comments did not differ significantly between the disclosure groups. Positive comments in the per capita payments group included, “OK, that sounds more appropriate. So there's no direct payment to him, but through the university. OK, I'm good…” and “I think those statements there are very important.” Positive comments in the equity group referred to the investigator's financial interest as a motivation for doing a good job (eg, “It looks like he'd have this real incentive for this thing to go real well, and I guess that's all to the good.”).
Reactions to the Possibility of Financial Benefit by Disclosure Group
There were 3 times as many clearly negative comments in the equity group as in the per capita payments group. In the per capita payments group, negative comments included the idea that the investigator might act inappropriately to secure future funding from the sponsor, and a more general suspicion of connections between pharmaceutical companies and physicians or investigators. In the equity group, the negative comments indicated discomfort with the possibility that the investigator might influence the results of the study to realize personal financial benefit, and doubts about the ability of the institutional review board to know the risks posed by the financial interest. Stronger language was used in the equity group than in the per capita payments group, including such terms as “disingenuous,” “unacceptable,” and “unethical.”
Eleven patients spontaneously reported that they would not participate in the hypothetical clinical trial because of the financial interest, and all but 1 of these patients were in the equity group.