To evaluate how ambiguity about the future benefits of a medical service affects patient and physician perceptions of the influence of conflicts of interest (COI) on shared decision making.
Four hundred thirty-nine 18-45 years old U.S. women (“patients”) were randomly assigned to 1 of 3 scenarios representing varying degrees of ambiguity about the future benefits of cord-blood stem cell banking – (A) only unambiguous benefits, (B) both unambiguous and ambiguous benefits, or (C) only ambiguous benefits – and reported their family's willingness to pay (WTP) for the service. They then stated their family's WTP again after learning about a physician's COI. Participants also rated the extent to which they trusted their physicians to make the decision for their family, and who should make the decision (both before and after the disclosure of COI).
Fifty-nine U.S. obstetric providers (“physicians”) were asked to predict a family's WTP in each scenario for families with income <$50K and $50-100K and then predicted what the family's WTP would be when a physician's COI was disclosed. They were also asked to rate the importance (0 = not important, 10 = very important) of avoiding financial relationships with companies that offer services that they might recommend to patients.
Disclosure of a physician's COI significantly reduced WTP by 26-53% (p < 0.05) in both income strata in Scenario C but only in families with income $50-100K in Scenarios A and B (See Figure 1). Trust in having the physician make the decision for their family and willingness to share the decision were both reduced significantly in all scenarios after COI disclosure.
Physicians predicted that WTPs would be reduced by 36-54% in all scenarios for both income strata (p < 0.05). Seventy-one percent of physicians indicated that it is absolutely unacceptable to have financial relationships with companies.
Physicians overestimated the effect of COI in low-income families when the service involved unambiguous benefits but not when the service offered only ambiguous benefits. The overestimation of the COI effect by physicians could be a barrier to COI disclosure during a shared decision making process. COI reduced patients' trust and willingness to share the decision with their physician, regardless of the ambiguity about future benefits.