Table 2.

Correlation between 6MWD (absolute value, m) and SSc patient characteristics (univariate linear regression).

Variables	Univariate Linear Regression
Variables	R²	p
Age	0.01	0.056
Sex	0.05	0.0001
BMI	0.001	0.496
Diffuse subtype^*	0.009	0.48
Performance status	0.169	< 0.0001
SHAQ	0.141	< 0.0001
mRSS	0.046	0.0003
Tendon friction rubs	0.069	< 0.0001
Arthralgia	0.076	0.0001
Muscle disease score	0.077	< 0.0001
Heart rate at rest	0.070	< 0.0001
Respiratory rate at rest	0.076	< 0.0001
NYHA functional classification	0.075	0.0008
Pulmonary function tests
FVC	0.076	< 0.0001
DLCO	0.199	< 0.0001
Transthoracic echocardiography
LVEF	0.085	< 0.0001
TRV	0.001	0.729
PASP	0.004	0.424
Laboratory tests
Hemoglobin level	0.162	< 0.0001
Serum creatinine	0.013	0.065
C-reactive protein	0.016	0.0399
Serum CPK	0.004	0.326

↵* Diffuse subtype according to Leroy and Medsger classification¹⁸. 6MWD: 6-minute walk distance; SSc: systemic sclerosis; BMI: body mass index; SHAQ: Scleroderma Health Assessment Questionnaire; mRSS: modified Rodnan skin score; NYHA: New York Heart Association; FVC: forced vital capacity; LVEF: left ventricular ejection fraction as measured by cardiac echography; TRV: tricuspid regurgitation peak velocity; PASP: pulmonary arterial systolic pressure; CPK: creatine phosphokinase.