An explicit values clarification task: development and validation

(a) To determine which of two values clarification exercises (VCE), based on theoretical decision rules used naturally by people, would be more helpful to patients making a treatment decision and (b) to evaluate the convergent validity of the most helpful VCE when part of a decision aid for the treatment of early-stage prostate cancer.

Two studies were completed. Study 1: Ninety community volunteers were assigned at random to one of three groups and all made a hypothetical treatment decision. Two groups received VCEs, one with a summary and one without, and the third was a control group. Study 2: In a multi-centre phase II trial, 69 patients used the decision aid that included the exercise ranked most helpful in Study 1. Decision aid assessments included the decisional conflict scale, treatment valuation assessment and regret.

Study 1: Most participants in each group ranked the VCE with the summary as most helpful. Study 2: VCE outputs, such as the size of the summary, were associated in predictable ways with the decision aid assessments.

The VCE ranked most helpful in Study 1 showed convergent validity with decision aid assessments.

With the interpretation of the VCE outputs now validated, a randomized controlled trial is required to determine if the exercise helps patients more than the aid without the exercise.