Table 4.

Mediation effects for outcome WOMAC pain over 36 months: Association of change in cartilage thickness loss over 24 months, with change in WOMAC knee

	Mediator: synovitis score change over 24 month Mean change in WOMAC Knee pain over 36 months	Mediator: BML score change over 24 months Mean change in WOMAC Knee pain over 36 months
Exposure: 0.1 mm Cartilage Thickness Loss over 24 months
Controlled Direct Effect	0.16 (−1.80, 2.12)	0.24 (−1.73, 2.19)
Indirect Effect	0.04 (−1.92, 2.00)	−0.003 (−1.96, 1.96)
Total Effect	0.16(−1.77, 2.15)	0.23(−1.73, 2.19)
Proportion Mediated	19.78% (−1.65%, 41.21%)	Proportion too small to calculate – not a mediator
Exposure: 0.05 mm Cartilage Thickness Loss over 24 months
Controlled Direct Effect	0.08 (−1.88, 2.04)	0.12 (−1.84, 2.08)
Indirect Effect	0.02 (−1.94, 1.98)	−0.002(−1.96, 1.96)
Total Effect	0.10(−1.86, 2.06)	0.12(−1.84, 2.08)
Proportion Mediated	19.78% (−1.65%, 41.21%)	Proportion too small to calculate – not a mediator

All models adjusted for age, sex, BMI, race, depressive symptoms (CESD).

Positive(+) coefficient indicates an increase in the outcome WOMAC pain.

Models for mediation by change in synovitis score adjusted for standard covariates above + baseline BML score.

Models for mediation by change in BML score adjusted for standard covariates above + baseline synovitis score.