A comparison of different strategies to collect standard gamble utilities.

OBJECTIVE

The authors performed a methodological comparison of the usual standard gamble with methods that could also be used in mailed questionnaires.

METHODS

Ninety-two diabetic patients valued diabetes-related health states twice. In face-to-face interviews, the authors used an iterative standard gamble (ISG) in which the probabilities were varied in a ping-pong manner and a self-completion method (SC) with top-down titration as search procedure (SC-TD) in 2 independent subsamples of 46 patients. Three months later, all patients received a mailed questionnaire in which the authors used the self-completion method with bottom-up (SCBU) and SC-TD as search procedures.

RESULTS

ISG and SCTD showed feasibility and consistency in the interviews. The ISG resulted in significantly higher utilities than the SC-TD. Two thirds of the mailed questionnaires provided useful results indicating some problems of feasibility. Utilities measured by SC-BU and SC-TD did not differ significantly showing procedural invariance. Further, patients indicated ambivalence when given the choice not to definitely state their preferences.

CONCLUSIONS

The results show that different strategies to collect standard gamble utilities can yield different results. Compared with the usually applied ISG, the SC method is feasible in interviews and provides a consistent alternative that is less costly when used in mailed questionnaires, although its practicability has to be improved in this later setting.