Health preferences measures: comparing Brazil SF-6D version with SF-36 derived versions, in patients with rheumatoid arthritis

Objective: To compare the preference measures derived from the SF-36 by different methods, with preference measures derived from the Brazilian version of the Short Form-6 Dimensions - Brazil (SF-6D Brazil). Methods: Observational cross-sectional study. Quality of life measures were applied: HAQ, SF-36 and SF-6D. We obtained preference measures derived from the SF-36 in accordance to the algorithms developed by Fryback, Nichol, Lundberg and Shmueli. Descriptive statistics and correlation coefficients were used to analyze the results. Results: We studied 200 patients with rheumatoid arthritis. The SF-6D and preferences derived from the SF-36 showed significant correlations with each other, with Pearson coefficients varying from 0.69 to 0.92 (p <0.01). Conclusion: The SF-6D and the different methods of preference derivation from the SF-36 showed moderate to strong correlations between them. Both application of the SF-36, as the SF-6D, may be important sources of preference measures for the implementation of economic analysis in health.