Assessing Medicare beneficiaries' strength-of-preference scores for health care options: how engaging does the elicitation technique need to be?

OBJECTIVE: The objective was to determine if participants' strength-of-preference scores for elective health care interventions at the end-of-life (EOL) elicited using a non-engaging technique are affected by their prior use of an engaging elicitation technique.
DESIGN: Medicare beneficiaries were randomly selected from a larger survey sample. During a standardized interview, participants considered four scenarios involving a choice between a relatively less- or more-intense EOL intervention. For each scenario, participants indicated their favoured intervention, then used a 7-point Leaning Scale (LS1) to indicate how strongly they preferred their favoured intervention relative to the alternative. Next, participants engaged in a Threshold Technique (TT), which, depending on the participant's initially favoured intervention, systematically altered a particular attribute of the scenario until the participant switched preferences. Finally, they repeated the LS (LS2) to indicate how strongly they preferred their initially-favoured intervention.
RESULTS: Two hundred and two participants were interviewed (189-198 were included in this study). The concordance of individual participants' LS1 and LS2 scores was assessed using Kendall tau-b correlation coefficients; scores of 0.74, 0.84, 0.85 and 0.89 for scenarios 1-4, respectively, were observed.
CONCLUSION: Kendall tau-b statistics indicate a high concordance between LS scores, implying that the interposing engaging TT exercise had no significant effects on the LS2 strength-of-preference scores. Future investigators attempting to characterize the distributions of strength-of-preference scores for EOL care from a large, diverse community could use non-engaging elicitation methods. The potential limitations of this study require that further investigation be conducted into this methodological issue.