Developing a Valuation Function for the Preference-Based Multiple Sclerosis Index: Comparison of Standard Gamble and Rating Scale

Objective: The standard gamble (SG) and rating scale (RS) are two approaches that can be employed to elicit health state preferences from patients in order to inform decision making. The objectives of this study were: (i) to contribute evidence towards the similarities and differences in the SG and the RS to reflect patient preferences, and (ii) to develop a multi-attribute utility function (MAUF) (i.e., scoring algorithm) for the PBMSI. Study Design: Two samples were recruited for the study. The first sample provided cross-sectional data to generate the preference weights which were then used to develop (D) the MAUFD. The distribution of SG and RS were compared across levels of perceived difficulty. The second sample provided additional data to validate (V) the MAUF, termed MAUFV. Results: The mean RS values ranged from 0.39 to 0.65, whereas the mean SG values were much higher ranging from 0.80 to 0.91. Correlations between the two methods were very low ranging from -0.29 to 0.15. Bland-Altman plots revealed the extent of differences in values produced by the two methods. Conclusion: In contemplating trade-offs in the selection of a preference-based elicitation approach for a MAUF that could guide clinical decision making, results suggest the RS is preferable in terms of feasibility and validity for MS patients. The PBMSI with patient preferences shows promise as a measure of health-related quality of life for MS.