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Table 2 Nonadjusted and adjusted associations between 6MWD and SSc characteristics

From: Factors associated with the 6-minute walk distance in patients with systemic sclerosis

  Nonadjusted Adjusted*
  β (95% CI) p β (95% CI) p
Male (vs female) 52.7 (21.8; 83.6) <10–3 76.9 (46.4; 107.4) <10–3
Age (per 1-year increment) –3.6 (–4.5; –2.8) <10–6 –3.9 (–4.8; –3.1) <10–6
Smoking history (vs no history) 31.8 (6.9; 56.7) 0.01 –11.2 (–34.9; 12.6) 0.36
BMI (per 1-kg/m2 increment) –4.1 (–6.4; –1.7) <10–3 –3.7 (–5.7; –1.6) <10–3
dcSSc (vs lcSSc) –0.7 (–32.8; 31.5) 0.97 –40.2 (–69.7; –10.8) 0.008
Disease duration since diagnosis (per 1-year increment) –1.8 (–3.3; –0.3) 0.02 0.7 (–0.8; 2.2) 0.38
Disease duration since first non-RP symptom (per 1-year increment) –2.3 (–3.8; –0.7) 0.004 –0.7 (–2.3; 0.8) 0.33
Disease duration since RP onset (per 1-year increment) –1.2 (–2.2; –0.2) 0.02 0.4 (–0.5; 1.4) 0.38
ACA (vs no ACA) –23.4 (–48.1; 1.3) 0.06 –9.8 (–35.5; 16.0) 0.46
ATA (vs no ATA) 0.1 (–31.0; 31.3) 0.99 –2.4 (–31.5; 26.8) 0.87
ARA (vs no ARA) 47.2 (–33.2; 127.7) 0.25 14.7 (–61.6; 90.9) 0.71
Anti-RNP antibodies (vs no anti-RNP antibodies) 3.7 (–52.2; 59.5) 0.90 –22.3 (–71.0; 26.4) 0.37
Abnormal nailfold capillaroscopy (vs normal) –18.1 (–86.7; 50.6) 0.61 –12.5 (–66.9; 41.8) 0.65
PAH (vs no PAH) –131.8 (–183.2; –80.3) <10–6 –112.0 (–155.9; –68.2) <10–3
ILD (vs no ILD)    0.02    0.08
 Limited ILD 16.4 (–13.0; 45.3)   14.2 (–13.8; 42.2)  
 Extensive ILD –52.3 (–95.6; –9.0)   –40.4 (–78.7; –2.1)  
DU (previously or at inclusion) (vs no DU) 13.2 (–11.6; 38.0) 0.30 –10.6 (–33.7; 12.6) 0.37
History of venous thrombosis (vs no history) –65.0 (–103.4; –26.5) 0.001 –52.5 (–87.3; –17.6) 0.003
History of arterial thrombosis (vs no history) –73.6 (–109.0; –38.1) <10–3 –43.5 (–76.4; –10.6) 0.01
History of cardiovascular disease (vs no history) –103.8 (–150.2; –57.5) <10–3 –65.0 (–108.2; –21.8) 0.003
Modified Rodnan skin score (per 1-point increment) –0.4 (–2.4; 1.7) 0.74 –0.9 (–3.1; 1.3) 0.42
Telangiectasia (vs no telangiectasia) –12.4 (–41.0; 16.1) 0.39 13.4 (–12.6; 39.4) 0.31
NYHA functional class (vs class I)    <10–6    <10–6
 NYHA class II –76.1 (–100.1; –52.2)   –61.7 (–83.8; –39.6)  
 NYHA class III –132.1 (–160.8; –103.3)   –108.1 (–134.5; –81.7)  
 NYHA class IV –227.4 (–303.1; –151.7)   –216.0 (–281.6; –150.4  
Cardiovascular symptoms (vs no symptoms) –49.8 (–94.6; –4.9) 0.03 –33.5 (–73.3; 6.2) 0.10
Joint symptoms (vs no symptoms) –29.4 (–54.3; –4.6) 0.02 –5.8 (–28.4; 16.8) 0.61
Muscle symptoms (vs no symptoms) –27.8 (–58.9; 3.4) 0.08 –16.1 (–44.0; 11.8) 0.26
Initial SpO2 (per 1% increment) 14.9 (9.2; 20.7) <10–6 11.4 (6.3; 16.4) <10–3
Final SpO2 (per 1% increment) 9.1 (5.5; 12.8) <10–3 7.2 (3.9; 10.4) <10–3
ΔSpO2 (per 1% increment) 4.7 (0.0; 9.4) 0.05 3.7 (–0.3; 7.8) 0.07
Initial Borg score (per 1-point increment) –22.5 (–33.3; –11.7) <10–3 –21.5 (–30.7; –12.3) <10–3
Final Borg score (per 1-point increment) –17.7 (–23.0; –12.4) <10–6 –13.8 (–18.6; –8.9) <10–6
ΔBorg score (per 1-point increment) –15.9 (–22.1; –9.6) <10–3 –10.4 (–16.3; –4.6) <10–3
Initial sBP (per 1-mmHg increment) –1.0 (–1.7; –0.2) 0.01 0.4 (–0.3; 1.2) 0.26
Final sBP (per 1-mmHg increment) –0.6 (–1.2; 0.1) 0.11 0.8 (0.1; 1.5) 0.02
ΔsBP (per 1-mmHg increment) 0.4 (–0.5; 1.3) 0.37 0.5 (–0.2; 1.3) 0.18
Initial dBP (per 1-mmHg increment) 9.1 (5.3; 12.8) <10–3 7.1 (3.9; 10.3) <10–3
Final dBP (per 1-mmHg increment) 0.5 (–0.7; 1.8) 0.42 0.1 (–1.0; 1.2) 0.91
ΔdBP (per 1-mmHg increment) 0.6 (–0.7; 1.8) 0.36 0.0 (–1.0; 1.1) 0.95
Initial HR (per 1-bpm increment) –1.9 (–2.9; –0.9) <10–3 –2.0 (–2.9; –1.2) <10–3
Final HR (per 1-bpm increment) –0.1 (–0.9; 0.7) 0.86 0.1 (–0.6; 0.8) 0.85
ΔHR (per 1-bpm increment) 2.1 (1.0; 3.2) <10–3 2.5 (1.6; 3.5) <10–6
Hemoglobin (per 1-g/dl increment) 26.6 (18.0; 35.2) <10–6 19.9 (11.5; 28.2) <10–3
ESR (per 1-mm/h increment) –2.3 (–3.1; –1.5) <10–6 –2.1 (–2.8; –1.3) <10–6
CRP (per 1-mg/L increment) –5.8 (–8.4; –3.3) <10–3 –5.8 (–8.0; –3.5) <10–3
Creatinin (per 1-mg/L increment) –3.6 (–8.0; 0.8) 0.11 –3.4 (–7.3; 0.5) 0.09
Estimated GFR (per 1-ml/min/1.73 m2 increment) 1.1 (0.6; 1.7) <10–3 0.0 (–0.6; 0.5) 0.97
Elevated Nt-pro-BNP (vs normal Nt-pro-BNP) –95.4 (–128.7; –62.1) <10–6 –66.5 (–98.4; –34.6) <10–3
CK (per 1-IU increment) 0.2 (0.0; 0.4) 0.11 0.2 (0.0; 0.3) 0.11
Ferritin (per 1-ng/ml increment) 0.0 (–0.1; 0.1) 0.55 0.0 (–0.1; 0.1) 0.84
Complement activation (vs no activation) 1.6 (–70.0; 73.3) 0.96 10.5 (–51.2; 72.1) 0.74
LVEF (per 1% increment) 2.1 (0.2; 4.1) 0.03 2.1 (0.4; 3.8) 0.02
LVDD (vs no LVDD) –69.6 (–96.6; –42.7) <10–6 –17.1 (–45.6; 11.4) 0.24
Valvular heart disease (vs no valvular heart disease) –22.5 (–59.3; 14.2) 0.23 26.2 (–7.5; 59.9) 0.13
Peak TRV (per 1-m/s increment) –62.3 (–101.0; –23.6) 0.002 –33.2 (–67.4; 1.1) 0.06
RA–RV pressure gradient (per 1-mmHg increment) –2.5 (–3.6; –1.5) <10–3 –1.8 (–2.8; –0.9) <10–3
Estimated sPAP (per 1-mmHg increment) –2.5 (–3.6; –1.4) <10–3 –1.9 (–2.9; –0.9) <10–3
RA area (per 1-cm2 increment) –4.7 (–8.2; –1.2) 0.01 –4.6 (–8.4; –0.7) 0.02
Abnormal IVC (vs normal IVC) –26.0 (–79.7; 27.6) 0.34 –22.5 (–68.9; 24.0) 0.34
Pericardial effusion (vs no pericardial effusion) –57.4 (–154.7; 39.9) 0.25 –95.3 (–188.3; –2.2) 0.05
TLC (per 1% increment) 1.0 (0.3; 1.8) 0.007 1.1 (0.4; 1.8) 0.002
FVC (per 1% increment) 0.4 (–0.2; 0.9) 0.20 1.2 (0.7; 1.7) <10–3
FEV1 (per 1% increment) 0.3 (–0.3; 0.9) 0.29 1.0 (0.5; 1.5) <10–3
FEV1/FVC (per 1% increment) 0.8 (–0.3; 2.0) 0.16 –0.2 (–1.3; 0.9) 0.68
DLCO (per 1% increment) 1.4 (0.8; 2.0) <10–3 1.5 (1.0; 2.0) <10–6
KCO (per 1% increment) 0.7 (0.0; 1.5) 0.04 1.2 (0.6; 1.9) <10–3
EScSG-AI score (per 1-point increment) –16.4 (–26.2; –6.5) 0.001 –14.6 (–23.5; –5.7) 0.001
Medsger severity score (per 1-point increment) –10.8 (–16.3; –5.4) <10–3 –82.9 (–99.8; –66.0) <10–6
HAQ-DI score (per 1-point increment) –104.6 (–122.0; –87.2) <10–6 –11.1 (–16.2; –6.1) <10–3
Positive chronotropic drug intake (vs no intake) –68.4 (–136.5; –0.3) 0.05 –38.7 (–98.6; 21.1) 0.21
Negative chronotropic drug intake (vs no intake) –48.1 (–74.7; –21.4) <10–3 –15.3 (–41.0; 10.5) 0.25
  1. β coefficients expressed in meters
  2. *Analyses adjusted on gender, age, BMI, disease duration, smoking history and SSc subtype
  3. 6MWD 6-minute walk distance, ACA anti-centromere antibodies, ARA anti-RNA polymerase III antibodies, ATA anti-topoisomerase I antibodies, BMI body mass index, CI confidence interval, CK creatin kinase, CRP C-reactive protein, dBP diastolic blood pressure, dc diffuse cutaneous, DLCO diffusing capacity of the lung for carbon monoxide, DU digital ulcers, EScSG-AI European Scleroderma Study Group Activity Index, ESR erythrocyte sedimentation rate, FEV1 forced expiratory volume during the first second, FVC forced vital capacity, GFR glomerular filtration rate, HAQ-DI Health Assessment Questionnaire—Disability Index, HR heart rate, ILD interstitial lung disease, IU international unit, IVC inferior vena cava, KCO diffusing coefficient for carbon monoxide, lc limited cutaneous, LVDD left ventricular diastolic dysfunction, LVEF left ventricle ejection fraction, NYHA New York Heart Association, PAH pulmonary arterial hypertension, RA right atrium, RP Raynaud phenomenon, RV right ventricle, sBP systolic blood pressure, sPAP systolic pulmonary arterial pressure, SpO 2 peripheral oxygen saturation, SSc systemic sclerosis, TLC total lung capacity, TRV tricuspid regurgitation velocity, Δ variation of