Integrating preferences into health status assessment for amyotrophic lateral sclerosis: the ALS Utility Index

We developed a preference-based measure, the Amyotrophic Lateral Sclerosis Utility Index (ALSUI), allowing computation of US population-based utility weights for the wide range of health states observed among ALS patients. A multi-attribute utility approach was used. An ALS Health State Classification System was developed comprising the following attributes with different severity levels: Speech and Swallowing (A1); Eating, Dressing, and Bathing (A2); Leg Function (A3); and Respiratory Function (A4). An internet-based survey was administered to a random sample of the US population to assess preferences for ALS health states based on this system using visual analog scale (VAS) and standard gamble (SG) questions. Using the VAS and SG data from 1374 individuals in the general population, utility functions were computed that corresponded to each severity level within A1, A2, A3, and A4. ALSUI scores for a given patient are computed by inputting his corresponding utility functions into the following multiplicative formula: ALSUI score = 1.06 x (A1 x A2 x A3 x A4) - 0.06 on a scale where 0.0 reflects death and 1.0 reflects healthy. This study provides a useful tool for classifying ALS patients and determining a general public-based utility score for ALS health states.