Table 2.
Predictive significance of baseline demographic and clinical characteristics for progression of percentage predicted FVC
| Prognostic variable | Main effect adjusted for follow-up time d | Interaction term of baseline FVC within 3 years of follow-up e | Interaction term between baseline FVC and up to 11 years of follow-up e | |||
|---|---|---|---|---|---|---|
| b (95% CI) | P value | b (95% CI) | P value | b (95% CI) | P value | |
| Follow-up time (years) | -0.96 (-1.31 to -0.61) | < 0.001 | NA | NA | NA | NA |
| Age at enrollment (years) | 0.12 (-0.09 to 0.33) | 0.263 | -0.01 (-0.07 to 0.07) | 0.914 | -0.01 (-0.04 to 0.02) | 0.592 |
| Ethnicity | ||||||
| White | 0 | 0 | ||||
| African American | -11.59 (-19 to -4.19) | 0.002 | 0.87 (-1.5 to 3.24) | 0.473 | 0.13(-0.87 to 1.13) | 0.799 |
| Hispanic | -0.82 (-7.24 to 5.59) | 0.802 | 0.36 (-1.9 to 2.6) | 0.752 | -0.54 (-1.45 to 0.37) | 0.243 |
| Other | -10.79 (-25.42 to 3.83) | 0.148 | 0.37 (-3.51 to 4.26) | 0.851 | -0.72 (-2.39 to 0.94) | 0.395 |
| Female sex | 6.76 (-0.38 to 13.9) | 0.063 | -2.19 (-4.42 to 0.05) | 0.055 | -0.57 (-1.51 to 0.37) | 0.233 |
| Body mass index | -0.03 (-0.53 to 0.47) | 0.905 | -0.11 (-0.26 to 0.03) | 0.138 | 0.01 (-0.06 to 0.07) | 0.789 |
| Current smoker | 4.89 (-2.1 to 11.88) | 0.17 | 0.91 (-1.16 to 2.99) | 0.388 | 0.08 (-0.8 to 0.95) | 0.867 |
| Ever smoker | 1.95 (-3.6 to 7.5) | 0.491 | 1.25 (-0.43 to 2.93) | 0.146 | 0.05 (-0.67 to 0.76) | 0.899 |
| Education level | 1.39 (-0.13 to 2.91) | 0.073 | 0.09 (-0.25 to 0.43) | 0.599 | -0.01 (-0.19 to 0.19) | 0.999 |
| Income level | 0.39 (-0.93 to 1.71) | 0.563 | 0.14 (-0.29 to 0.57) | 0.523 | -0.03 (-0.2 to 0.14) | 0.746 |
| Disease durationa | -0.26 (-1.97 to 1.45) | 0.767 | 0.03 (-0.49 to 0.54) | 0.924 | -0.01 (-0.23 to 0.21) | 0.94 |
| Disease duration (alternative method)b | 0.54 (0.04 to 1.04) | 0.034 | 0.04 (-0.09 to 0.17) | 0.582 | -0.01 (-0.07 to 0.05) | 0.753 |
| Limited disease | 7.08 (1.57 to 12.59) | 0.012 | -0.66 (-2.35 to 1.0.03) | 0.442 | 0.03 (-0.68 to 0.74) | 0.932 |
| Autoantibodies | ||||||
| ANA | -2.07 (-16.01 to 11.87) | 0.771 | 0.46 (-3.34 to 4.27) | 0.812 | -1.07 (-2.74 to 0.61) | 0.214 |
| ACA | 22.73 (14.82 to 30.65) | < 0.001 | -1.74 (-4.29 to 0.81) | 0.182 | -0.39 (-1.43 to 0.65) | 0.463 |
| ATA | -12.49 (-19.44 to -5.53) | < 0.001 | -2.49 (-4.62 to -0.36) | 0.022 | -0.72 (-1.63 to 0.19) | 0.121 |
| Anti-RNA polymerase III | -0.75 (-7.35 to 5.86) | 0.824 | 0.22 (-1.69 to 2.13) | 0.825 | 0.02 (-0.79 to 0.84) | 0.955 |
| Anti-U1-ribonucleoprotein | -1.32 (-10.18 to 7.54) | 0.771 | 0.47 (-2.96 to 3.9) | 0.788 | 0.08 (-1.24 to 1.4) | 0.901 |
| Anti-Ro | -1.83 (-18.42 to 14.75) | 0.829 | 4.63 (-0.29 to 9.56) | 0.065 | 0.89 (-1.16 to 2.94) | 0.394 |
| Anti-fibrillarin | -3.42 (-12.26 to 5.41) | 0.448 | -0.49 (-3.58 to 2.58) | 0.751 | -0.06 (-1.35 to 1.22) | 0.921 |
| Modified RSS | -0.41 (-0.65 to -0.17) | 0.001 | -0.95 (-2.37 to 0.47) | 0.191 | 0.01 (-0.02 to 0.04) | 0.43 |
| VAS for dyspnea | -1.98 (-2.86 to -1.1) | < 0.001 | 0.21 (-0.1 to 0.52) | 0.193 | 0.05 (-0.09 to 0.19) | 0.471 |
| VAS for pain | -0.35 (-0.91 to 0.21) | 0.221 | 0.07 (-0.07 to 0.22) | 0.331 | 0.05 (-0.02 to 0.12) | 0.184 |
| Teleagiectasia | ||||||
| Facial/oral | 2.78 (-2.76 to 8.31) | 0.326 | 1.24 (-0.44 to 2.91) | 0.148 | 0.35 (-0.35 to 1.05) | 0.329 |
| Palmar | 1.34 (-4.65 to 7.33) | 0.661 | 1.09 (-0.68 to 2.88) | 0.225 | 0.51 (-0.22 to 1.25) | 0.176 |
| Dysphagia | 1.39 (-4.14 to 6.93) | 0.621 | 0.13 (-1.55 to 1.82) | 0.879 | 0.3 (-0.41 to 1.01) | 0.404 |
| sPAP increase by echo | 0.2 (-13.36 to 13.75) | 0.977 | 3.51 (0.27 to 6.74) | 0.033 | 0.16 (-0.40 to 3.51) | 0.119 |
| Auscultatory rales | -16.64 (-22.92 to -10.36) | < 0.001 | 0.45 (-1.49 to 2.39) | 0.651 | -0.32 (-1.17 to 0.54) | 0.464 |
| Fibrosis on CXR | -26.67 (-33.07 to -20.27) | < 0.001 | 1.09 (-1.35 to 3.54) | 0.379 | -0.8 (-1.85 to 0.25) | 0.137 |
| Baseline FVC%c | 0.94 (0.86 to 1.02) | < 0.001 | -0.01 (-0.07 to 0.06) | 0.869 | -0.02 (-0.4 to 0.01) | 0.066 |
| Baseline FEV1% | 0.94 (0.87 to 1.01) | < 0.001 | 0.01 (-0.07 to 0.08) | 0.874 | -0.01(-0.03 to 0.01) | 0.222 |
| Baseline DLco% | 0.46 (0.36 to 0.57) | < 0.001 | -0.01 (-0.01 to 0.01) | 0.387 | 0.01 (-0.01 to 0.02) | 0.655 |
| Baseline TLC% | 0.82 (0.73 to 0.92) | < 0.001 | 0.01 (-0.01 to 0.01) | 0.175 | -0.01 (-0.03 to 0.01) | 0.389 |
| FEV1/FVC <0.75 | 9.16 (2.88 to 15.45) | 0.004 | -1.52 (-5.98 to 2.94) | 0.505 | -0.21 (-0.98 to 0.56) | 0.597 |
| Creatinine ≥1.5 | -6.91 (-24.89 to 11.07) | 0.452 | 4.88 (-1.35 to 11.11) | 0.125 | -0.35 (-3.52 to 2.82) | 0.828 |
| CPK >200 | -7.81 (-15.5 to -0.13) | 0.046 | 2.1 (-0.26 to 4.47) | 0.081 | 0.49 (-0.52 to 1.51) | 0.337 |
| Hematocrit | -0.01 (-0.64 to 0.64) | 0.999 | -2.75 (-11.14 to 5.65) | 0.521 | -0.02 (-0.11 to 0.07) | 0.685 |
| White blood cells | -0.91 (-1.89 to 0.06) | 0.067 | -0.01 (-0.01 to 0.01) | 0.072 | 0.04 (-0.07 to 0.16) | 0.465 |
| Elevated platelet count | -3.37 (-9.62 to 2.86) | 0.289 | 0.08 (-1.64 to 1.8) | 0.928 | -0.22 (-1.03 to 0.59) | 0.599 |
ACA, anti-centromere antibodies; ANA, anti-nuclear antibodies; ATA, anti-topoisomerase antibodies; b, regression coefficient; CI, confidence interval; CPK, creatine phosphokinase; CXR, Chest X-ray; DLco, lung diffusion capacity for carbon monoxide; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; RSS, Rodnan Skin Score; sPAP, systolic pulmonary arterial pressure; TLC, total lung capacity; VAS, visual analog scale. aDisease onset defined as first non-Raynaud's phenomenon symptom. bDisease onset defined as first symptom attributable to SSc. cBaseline FVC measurements were not included in the outcome variable for this analysis. dMain effect adjusted for follow-up time. eInteraction term between the follow-up time and the respective baseline variable (outcome: rate of decline in FVC). Bold data represent significant associations (P < 0.05).