Association of anti-CCP with high attenuation areas and interstitial lung abnormalities on CT
| Anti-CCP quartile | Per cent difference (95% CI) in HAA per doubling of anti-CCP | p Value | |||||
|---|---|---|---|---|---|---|---|
| <0.17 U/mL | 0.17–0.2 U/mL | 0.21–0.5 U/mL | >0.5 U/mL | p Value for trend | |||
| No. of subjects | 1706 | 1696 | 1711 | 1615 | |||
| HAA, cm3, median (IQR) | 119.7 (100.7 to 144.0) | 122.4 (101.8 to 147.2) | 121.2 (102.2 to 145.8) | 121.4 (101.8 to 145.7) | |||
| Per cent difference (95% CI) in HAA | |||||||
| Unadjusted | 0 (Ref) | 2.54 (0.54 to 4.58) | 1.31 (−0.67 to 3.32) | 1.72 (−0.29 to 3.77) | 0.42 | 0.13 (−0.73 to 0.99) | 0.77 |
| Adjusted* | 0 (Ref) | 2.34 (0.75 to 3.95) | 1.33 (−0.25 to 2.93) | 2.35 (0.60 to 4.13) | 0.06 | 0.57 (−0.12 to 1.27) | 0.11 |
| Never smoker | 0 (Ref) | 1.17 (−1.21 to 3.61) | −0.73 (−3.07 to 1.67) | 0.68 (−1.94 to 3.38) | 0.70 | −0.40 (−1.55 to 0.77) | 0.50 |
| Ever smoker | 0 (Ref) | 2.83 (0.73 to 4.99) | 2.66 (0.52 to 4.85) | 3.64 (1.29 to 6.05) | 0.02 | 1.31 (0.45 to 2.18) | 0.003 |
| Prevalence ratio (95% CI) for ILA per doubling of anti-CCP | |||||||
| No. of subjects | 603 | 589 | 625 | 582 | |||
| ILA prevalence, % (95% CI) | 14.3 (11.7 to 17.3) | 12.1 (9.7 to 14.9) | 11.4 (9.1 to 14.1) | 12.5 (10.1 to 15.5) | |||
| Prevalence ratio (95% CI) for ILA | |||||||
| Unadjusted | 1 (Ref) | 0.85 (0.63 to 1.13) | 0.80 (0.59 to 1.07) | 0.88 (0.66 to 1.18) | 0.70 | 1.08 (0.95 to 1.23) | 0.25 |
| Adjusted† | 1 (Ref) | 0.88 (0.66 to 1.17) | 0.81 (0.61 to 1.08) | 0.82 (0.62 to 1.10) | 0.33 | 1.05 (0.91 to 1.20) | 0.52 |
| Never smoker | 1 (Ref) | 0.73 (0.47 to 1.14) | 0.65 (0.41 to 1.003) | 0.57 (0.35 to 0.92) | 0.06 | 0.66 (0.37 to 1.19) | 0.17 |
| Ever smoker | 1 (Ref) | 0.96 (0.66 to 1.40) | 0.93 (0.64 to 1.37) | 1.02 (0.70 to 1.47) | 0.81 | 1.13 (1.02 to 1.24) | 0.02 |
*Adjusted for age, sex, race, study site, BMI, waist circumference, pack-years of smoking, current smoking status, total volume of imaged lung, per cent emphysema and tube current.
†Adjusted for age, sex, race, pack-years of smoking and current smoking status.
p Value for interaction of anti-CCP and smoking was 0.02 in the HAA analysis and 0.01 in the ILA analysis.
Anti-CCP, anti-cyclic citrullinated peptide antibody; HAA, high attenuation areas; ILA, interstitial lung abnormalities.