Fig. 2

SF-6D disutility scores in relation to symptomatic and radiographic knee OA definitions. a 2-scale symptomatic knee OA (K-L grade ≥ 2 and frequent knee pain in the same knee in at least one knee) b 2-scale radiographic knee OA (K-L grade ≥ 2 in at least one knee) c 3-scale symptomatic knee OA (K-L grade ≥ 2 and frequent knee pain in the same knee) d 3-scale radiographic knee OA (K-L grade ≥ 2). Disutility of the best health state possible (no OA) 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 (no OA)