Feasibility and reliability of a mailed questionnaire to obtain visual analogue scale valuations for health states defined by the Health Utilities Index Mark 3

To establish the generalizability (external validity) of the Health Utilities Index Mark 3 (HUI3) as a single-summary score generic outcome measure in numerous countries/subgroups (including children), repeated studies of community preferences should be performed in various settings. In performing multiple HUI3 studies, a mailed questionnaire approach, if feasible and reliable, might be substituted for oral interviews. in the present study, we assessed the feasibility and reliability of a mailed questionnaire approach originally developed for the EQ-5D, for the purpose of collecting Visual Analogue Scale (VAS) valuations from parents as surrogate responders for 65 pediatric HUI3 health states and for the state of being dead. Untransformed mean VAS scores of the health states and scores converted into preliminary Standard Gamble (SG)-utilities were compared with Canadian and French multiattribute utility estimates. A random sample of 1920 parents of schoolchildren (aged 4 to 13) received a mailed questionnaire. Each parent was asked to rate 6 HUI3 health states on a 0 to 100 VAS. Response was 70%. Mean completion time was 20 minutes (SD 9). The questionnaire was rated difficult by only 9%. The current format was, however, inappropriate for valuing the state of being dead. Interrater reliability of health state valuations was .87. Spearman's rank correlations, Pearson-R correlations and intra class correlation coefficients (ICCs) between untransformed VAS valuations and Canadian/French utility estimates were greater than or equal to.87. However, preliminary SG-utilities showed diminished ICCs (.71 to .72). The data support the feasibility and reliability of mailed HUI3 valuation questionnaires to a considerable extent, but further methodological studies regarding other formats and different populations are recommended.