Table 4

Relationship between STV and pain scores

Effect of change in STV on outcome (mm3)
Model outcomeb* (95% CI)p ValueβChange in R2 overall†
KOOS pain subscale score (0–100), mean (SD)−1.13 (−1.87 to −0.39)0.003−0.280.02
Pain on nominated activity VAS (0–10), mean (SD)0.17 (0.05 to 0.29)0.0060.320.04
  • Linear regression analysis.

  • *b coefficients have been scaled to reflect a change in STV of 1000 mm3. The models used to derive these coefficients were yit=Xit1β+Xit2β+αi+uit, where yit =either KOOS pain subscale score or VASNA, and Xit1=STV, Xit2=study visit (coded as dummy variables), αi=subject, and uit=error. Coefficients for study visit dummy variables not presented, for clarity.

  • †‘Change in R2 overall’=Difference in overall R2 between a fixed-effect panel model including study visit alone as the predictor and a fixed-effect panel model with study visit and STV as predictors—shows the amount of additional variance explained by adding STV into the fixed-effect regression models.

  • b, unstandardised coefficient; KOOS, Knee Injury and Osteoarthritis Outcome Score; STV, synovial tissue volume; VAS, Visual Analogue Scale; β, standardised coefficient.