Table 3.

Associations Between FGF-21 Values and Muscle and Strength Parameters

	Effect on Outcome at Baseline			Effect on Rate of Change of Outcome
	β (95% CI)	P	N	β (95% CI)	P	N
Muscle Density Z-Score
FGF-21 (Continuous)	−0.024 (−0.27, 0.22)	0.84	105	−0.056 (−0.12, 0.008)	0.08	76
FGF-21 in Top Quartile	0.022 (−0.52, 0.56)	0.94	105	−0.074 (−0.20, 0.056)	0.26	76
Muscle Area Z-Score
FGF-21 (Continuous)	−0.019 (−0.32, 0.28)	0.90	101	−0.049 (−0.10, 0.006)	0.08	70
FGF-21 in Top Quartile	0.072 (−0.59, 0.73)	0.83	101	−0.034 (−0.15, 0.081)	0.55	70
Peak Isometric Torque, Extension at Knee (ft-lbs)
FGF-21 (Continuous)	−1.40 (−7.61, 4.81)	0.66	107	−1.05 (−3.02, 0.92)	0.29	72
FGF-21 in Top Quartile	−4.93 (−18.57, 8.71)	0.48	107	−2.70 (−6.84, 1.43)	0.20	72
Peak Isometric Torque, Flexion at Knee (ft-lbs)
FGF-21 (Continuous)	−1.19 (−4.54, 2.15)	0.48	107	−1.64 (−3.54, 0.26)	0.09	72
FGF-21 in Top Quartile	−2.18 (−9.54, 5.19)	0.56	107	−0.13 (−4.24, 3.99)	0.95	72
Grip Strenqth (kq)
FGF-21 (Continuous)	−0.031 (−1.99, 1.93)	0.98	108	0.10 (−0.62, 0.83)	0.77	81
FGF-21 in Top Quartile	−1.77 (−6.03, 2.50)	0.41	108	−1.39 (−2.79, 0.014)	0.05	81

Legend: All models include adjustments for age, gender, visceral fat area, current smoking, and methotrexate use (all at baseline). Models involving strength outcomes (extension at knee, flexion at knee, and grip) also include an adjustment for height at baseline, β coefficients represent differences associated with a 1 SD higher FGF-21 level at baseline.