Fig. 3

SF-6D disutility scores in relation to 5- and 9-scale radiographic knee OA definitions. a 5-scale radiographic knee OA (the highest K-L grade in both knees) or b 9-scale radiographic knee OA (mean of K-L grades in both knees). Disutility of the best health state possible (K-L grade 0) is set as the horizontal reference line (dotted). Other horizontal lines (dotted) are set in 0.027 point intervals representing 1.0 MID (minimally important difference). Error bars are 95% confidence intervals. The mean difference is significant at the 0.05 level (*) in comparison to the best health state (K-L grade 0)