Doctors' decisions when faced with contradictory patient advance directives and health care proxy opinion: a randomized vignette-based study.

Context: Sometimes a written advance directive contradicts the opinion of a health care proxy. How this affects doctors' decision making is unknown.

Objectives: To quantify the influence of contradictory instructions on doctors' decisions.

Methods: All the generalists and internists in French-speaking Switzerland were mailed the questionnaire. Respondents (43.5%) evaluated three vignettes that described medical decisions for incapacitated patients. Each vignette was produced in four versions: one with an advance directive, one with a proxy opinion, one with both, and one with neither (control). In the first vignette, the directive and proxy agreed on the recommendation to forgo a medical intervention; in the second, the advance directive opposed, but the proxy favored the intervention; and in the third, the roles were reversed. Each doctor received one version of each vignette, attributed at random. The outcome variables were the doctor's decision to forgo the medical intervention and the rating of the decision as difficult.

Results: Written advance directives and proxy opinions significantly influenced doctors' decision making. When both were available and concordant, they reinforced each other (odds ratio [OR] of forgoing intervention 35.7, P < 0.001 compared with no instruction). When the directive and proxy disagreed, the resulting effect was to forgo the intervention (ORs 2.1 and 2.2 for the two discordant vignettes, both P < 0.001). Discordance between instructions was associated with increased odds of doctors rating the decision as difficult (both ORs 2.0, P ≤ 0.001).

Conclusion: Contradictions between advance directives and proxy opinions result in a weak preference for abstention from treatment and increase the difficulty of the decision.