	Cox model using baseline DLCO as covariate	Cox model using DLCO as time-dependent covariate	Joint model using DLCO as a time-dependent covariate
	HR (95% CI)	HR (95% CI)	HR (95% CI)
DLCO models
Baseline MRSS	1.56 (0.92 to 2.67)	1.86 (1.00 to 3.47)	1.85 (1.07 to 3.19)*
Age (years)	1.08 (1.03 to 1.13)***	1.08 (1.02 to 1.15)**	1.07 (1.03 to 1.12)**
DLCO%-predicted	0.95 (0.85 to 1.06)	0.83 (0.72 to 0.96)*	0.84 (0.76 to 0.94)**
AIC	249	150	360

AIC, Akaike information criterion; DLCO, single-breath diffusing capacity for carbon monoxide; FVC, forced vital capacity; MRSS, Modified Rodnan Skin Score.
*P<0.01, **P<0.01, ***P<0.001.
†P<0.0001.