Methods: Health state values obtained from EuroQol with US and UK scoring (EQ5D-US, EQ5D-UK), the Health Utilities Index with Mark 2 and 3 scoring (HUI2, HUI3), and SF-36-derived Quality of Well Being Scale (eQWB) and SF-6D at baseline (V0) and follow-up (Vf ) were used to compute change scores (Vf -V0 ) for each system. Paired t-tests were used to assess differences in mean change scores between system pairs. Spearman correlations were used to describe associations between change scores. We estimated effect size (mean change /standard deviation (SD) at baseline), standardized response mean (SRM = mean change /SDchange _score), and minimally important difference (MID) for each system. MID was defined using the mean change score for those who reported minor progress or worsening of their spine problem at follow-up.
Results: Among 1,696 individuals ages 18-93 (mean age 55, 50% female), 80% reported improvement by global transition rating with MID computed among the 446 who reported minimal change. Marked differences between change scores were noted for all systems except EQ5D-US and HUI2. All systems were strongly correlated with each other (0.6 to1.0). Results were:
|Mean Score Change (95%CI)||Effect Size||SRM||MID|