Table 3.

Predictive significance of Severity Index subscales for progression of FVC

Medsger Severity Index	Main effect adjusted for follow-up time		Interaction term of baseline FVC within 3 years of follow-up		Interaction term between baseline FVC and up to 11 years of follow-up
	b (95% CI)	P value	b (95% CI)	P value	b (95% CI)	P value
General	-0.22 (-3.65 to 3.19)	0.897	0.0 (-0.01 to 0.01)	0.463	0.01 (-0.48 to 0.5)	0.972
Peripheral vascular	-0.81 (-3.31 to 1.69)	0.525	0.0 (-0.01 to 0.01)	0.436	0.1 (-0.21 to 0.41)	0.513
Skin	-3.61 (-7 to -0.22)	0.037	0.58 (-2.41 to 1.24)	0.531	0.17 (-0.27 to 0.61)	0.449
Joint/tendon	-2.14 (-4.48 to 0.19)	0.072	-0.19 (-1.15 to 0.75)	0.682	-0.06 (-0.37 to 0.25)	0.712
Muscle	-5.61 (-12.22 to 1)	0.096	-0.32 (-1.27 to 0.63)	0.504	0.23 (-0.61 to 1.07)	0.588
Gastrointestinal tract	-0.26 (-4.58 to 4.06)	0.905	0.0 (-0.01 to 0.01)	0.369	0.02 (-0.61 to 0.65)	0.955
Lung	-9.73 (-11.91 to -7.55)	< 0.001	0.0 (-0.01 to 0.01)	0.707	-0.29 (-0.62 to 0.03)	0.077
Heart	-1.98 (-6.17 to 2.2)	0.353	0.0 (-0.01 to 0.01)	0.321	0.24 (-0.44 to 0.92)	0.493
Kidney	0.62 (-6.84 to 8.09)	0.87	0.0 (-0.01 to 0.01)	0.128	-0.22 (-1.64 to 1.19)	0.756

b, regression coefficient; CI, confidence interval; FVC, forced vital capacity. Bold data represent significant associations (P < 0.05).