Supplementary Table S4 shows the results of an alternative Cox regression analysis that was adjusted for the duration of ILD, with the dependent variable progression of RA-ILD. The only variable that was associated with the progression of RA-ILD in this model was IL-18 in pg/mL (β = 0.227; p = 0.004) (Figure 2). The gene discussed is IL18; the disease is interstitial lung disease.