Skip to main content

Table 4 The mediation effect of changes in DCE-MRI perfusion variables for changes in KOOS pain

From: Exercise-induced pain changes associate with changes in muscle perfusion in knee osteoarthritis: exploratory outcome analyses of a randomised controlled trial

  Estimate (95%CIs) and P-valuea Proportion mediated (95% CI)a
Total effect 10.7 (3.3 to 18.1), P = 0.006
Mediator
 TotalMuscle
  Nvoxel% 2.1 (−0.1 to 9.6), P = 0.116 0.20 (−0.02 to 1.23)
  IRExNvoxel 2.3 (−0.4 to 6.3), P = 0.092 0.21 (−0.06 to 0.81)
  IRExNvoxel% 1.9 (−1.2 to 6.0), P = 0.230 0.18 (−0.15 to 0.88)
  MExNvoxel 2.1 (−0.1 to 7.0), P = 0.094 0.19 (−0.02 to 0.88)
  MExNvoxel% 2.1 (−0.1 to 9.5), P = 0.116 0.20 (−0.01 to 1.03)
 Extensor
  Nvoxel% 0.6 (−0.7 to 4.3), P = 0.476 0.05 (−0.07 to 0.54)
  IRExNvoxel 0.9 (−1.8 to 3.1), P = 0.468 0.09 (−0.26 to 0.35)
  IRExNvoxel% 1.3 (−3.6 to 5.1), P = 0.496 0.12 (−0.43 to 0.53)
  MExNvoxel 0.2 (−0.6 to 2.3), P = 0.630 0.02 (−0.07 to 0.30)
 MExNvoxel% 0.5 (−0.7 to 3.9), P = 0.494 0.05 (−0.09 to 0.44)
 Flexor
  Nvoxel% 2.8 (0.0 to 10.8), P = 0.060 0.26 (0.00 to 1.38)
  IRExNvoxel 2.8 (0.0 to 7.7), P = 0.048 0.26 (0.00 to 1.24)
  IRExNvoxel% 1.8 (−0.7 to 5.5), P = 0.182 0.17 (−0.08 to 0.82)
  MExNvoxel 3.0 (0.1 to 12.3), P = 0.040 0.28 (0.01 to 1.71)
  MExNvoxel% 3.0 (0.1 to 11.5), P = 0.038 0.28 (0.01 to 1.46)
  1. aThe mediation effect of changes in the DCE-MRI perfusion variables for changes in KOOS pain were calculated in a post-hoc mediation analysis using a model-based approach with nonparametric bootstrap for variance estimation. The models were adjusted for the same variables as the primary analysis (i.e. baseline KOOS pain and gender). An average causal mediation effect was estimated
  2. Abbreviations: CI Confidence interval, KOOS The Knee Injury and Osteoarthritis Outcome Score, DCE-MRI Dynamic contrast enhanced magnetic resonance imaging, Total Muscle VOI A volume of interest consisting of the summed and averaged peri-articular knee extensor and flexor muscle ROIs, Extensor VOI A volume of interest consisting of summed and averaged ROIs of the peri-articular knee extensor muscles, Flexor VOI A volume of interest consisting of summed and averaged ROIs of the peri-articular knee flexor muscles, Nvoxel% Proportion of Highly Perfused Voxels (%), IRExNvoxel Initial Rate of Enhancement Composite Score, IRExNvoxel% Initial Rate of Enhancement Index, MExNvoxel Maximal Enhancement Composite Score, MExNvoxel% Maximal Enhancement index