Consistency Between Three Different Ways of Administering the Short Form 6 Dimension Version 2.

Area of Science:

• Health Economics
• Psychometrics
• Quality of Life Research

Background:

• The Short Form 6 Dimension (SF-6D) is a health utility instrument derived from the SF-36v2 quality of life survey.
• It is used to calculate quality-adjusted life years (QALYs) on a scale of 0 to 1.
• The SF-6Dv2 is a newer version of the SF-6D instrument.

Purpose of the Study:

• To assess the consistency of respondent answers using three different administration methods for the SF-6Dv2.
• To evaluate potential biases introduced by shorter or independent administration formats.

Main Methods:

• SF-6Dv2 utility values were generated using three approaches: the full SF-36v2 questionnaire (SF-6Dv2SF-36), a 10-item subset (SF-6Dv2ind-10), and a 6-item independent version (SF-6Dv2ind-6).
• The order of these three instruments was randomized among 782 respondents in Quebec, Canada.
• Data from 697 fully completed surveys were analyzed for consistency.

Main Results:

• High consistency was observed across the three SF-6Dv2 administration methods, with a mean weighted kappa of 0.79.
• The maximal difference in utility values was between SF-6Dv2ind-10 and SF-6Dv2ind-6 (0.016).
• Minimal difference was found between SF-6Dv2SF-36 and SF-6Dv2ind-10 (0.002), indicating high agreement.

Conclusions:

• The SF-6Dv2 demonstrates robust consistency regardless of the administration method.
• While using the full SF-36v2 questionnaire is still recommended, shorter or independent versions of the SF-6Dv2 introduce only minimal bias.
• These findings support the flexibility of using the SF-6Dv2 in various research and clinical contexts.