Table 3. Optimism-corrected area under the curve for predicting RA-ILD risk by adding novel biomarkers and the MUC5B promoter variant to clinical factors.

Model*	Apparent AUC (95% CI)
Demographic	0·58 (0·51,0·65)	0·07	0·51 (0·45, 0·57)
MUC5B promoter variant	0·60 (0·53,0·67)	0·05	0·55 (0·48, 0·61)
Lifestyle	0·68 (0·62,0·75)	0·04	0·64 (0·58, 0·70)
RA factors	0·74 (0·68,0·81)	0·06	0·68 (0·62, 0·74)
Clinical factors combined	0·79 (0·73,0·85)	0·06	0·73 (0·67, 0·78)
Established RA-ILD factors	0·80 (0·74, 0·85)	0·07	0·73 (0·67, 0·78)
Novel biomarkers (N=6)	0·86 (0·81,0·92)	0·03	0·84 (0·79, 0·89)
All factors combined	0·90 (0·85,0·94)	0·06	0·84 (0·80, 0·88)

AUC = area under curve, BMI = body mass index, CI = confidence interval, cit = citrullinated, CRP = C-reactive protein, DAS = disease activity score, DMARD = disease-modifying anti-rheumatic drug, H = histone, Ig = immunoglobulin, ILD = interstitial lung disease, MDHAQ = multi-dimensional health assessment questionnaire, OR = odds ratio, RA = rheumatoid arthritis, RF = rheumatoid factor

^*Demographic = age, race and ethnicity, education; Lifestyle = BMI, smoking pack-years; RA factors = RA duration, RF, anti-CCP, bone erosion, rheumatoid nodules, methotrexate use, glucocorticoid use, biologic DMARD use, DAS28-CRP, MDHAQ; Clinical factors combined = demographic + lifestyle + RA factors; Established RA-ILD factors = demographic + lifestyle + RA factors + MUC5B; Novel biomarkers = H4 33–48 cit 39 (IgA2), H2A/a-2 1–20 cit (IgA2), Filaggrin 48–65 cit2 cyclic (IgG), H2A/a 1–20 cyclic (IgA2), H2A/a-2 1–20 (IgA2), Filaggrin 48–65 cyclic (IgG)