Table 4.

Multiple linear regression analysis assessing the association of anti-CCP2 titers with the ground-glass and fibrosis scores observed in HRCT adjusting by selected variables.

Independent variables	HRCT
	Enter		Forward Stepwise
	β	P value	β	P value
Ground-glass score
Age, years	0.026	0.85	—	Not in the model
Disease duration, years	0.068	0.90	—	Not in the model
DAS28	0.851	0.53	—	Not in the model
Anti-CCP2 titers	0.048	0.03	0.053	0.02
MTX treatment duration, years	−0.299	0.85	—	Not in the model
Fibrosis score
Age, years	−0.069	0.19	—	Not in the model
Disease duration, years	−0.510	0.01	−0.506	0.01
DAS28	0.430	0.41	—	Not in the model
Anti-CCP2 titers	0.065	<0.001	0.070	<0.001
MTX treatment duration, years	0.879	<0.001	1.035	<0001

Anti-CCP2 titers: anti-cyclic citrullinated peptide antibodies titers (second generation); DAS28: disease activity score; HAQ-Di: Health Assessment Questionnaire; MTX: methotrexate. Dependent variables: first model: ground-glass score, second model: fibrosis score. Covariates included in this analysis were those quantitative variables that had statistical significance in the univariate analysis or were considered with biologic plausibility to explain the severity of ILD in HRCT.