Table 4.

Association of Anti-CCP with High Attenuation Areas and Interstitial Lung Abnormalities on CT

	Anti-CCP Quartile					Percent difference (95% CI) in HAA per doubling of anti-CCP	P-value
	< 0.17 U/mL	0.17 to 0.2 U/mL	0.21 to 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)
Percent 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, percent 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.