*2.4. HRCT Abnormalities*

Of the entire cohort, 62.5% had HRCT abnormalities. The most frequently detected abnormality was the presence of nodules, followed by evidence of fibrosis. The less frequent abnormality was the presence of air trapping. There were no differences in the frequency of the various HRCT

abnormalities according to smoking status or, among LSRA patients, to treatment with methotrexate (MTX). The frequencies of HRCT abnormalities are shown in Table 3.

**Table 3.** Frequencies of total and selected lung abnormalities at high-resolution computed tomography (HRCT) scan.


Data are reported as percentage of the total. *P* values intended for comparisons between ND, ERA and LSRA subgroups of participants. \*: post hoc test *p* < 0.05 vs. ND; †: post hoc test *p* < 0.05 vs. ERA. Abbreviations: ND, no disease subjects; ERA, early rheumatoid arthritis patients; LSRA, long standing rheumatoid arthritis patients.

Subgroup analysis revealed significantly higher rates of overall HRCT abnormalities, nodules, emphysema and fibrosis among LSRA patients compared with the other subgroups (*p* = 0.001, *p* = 0.004, *p* = 0.02 and *p* = 0.003, respectively). The same differences in HRCT total abnormalities and nodules were also observed when limiting the analysis to those patients who never smoked (*p* = 0.049 and *p* = 0.016, respectively). Current and former smokers showed a significantly higher frequency of fibrosis compared with subjects who never smoked (*p* = 0.03), with a relative risk of 2.77 (CI 95% 1.054–8.359). Of note, no difference in fibrosis prevalence was found based on MTX treatment.
