Multivariate logistic analysis showing covariates independently associated with RA-ILD development
| Primary analysis, RA-ILD onset after any csDMARD exposure (n=67) | Wald test | Extended cohort, including RA-ILD onset prior to any csDMARD (n=92) | Wald test | |
| OR (95% CI) | P value | OR (95% CI) | P value | |
| Methotrexate exposure | 0.85 (0.49 to 1.49) | 0.578 | 0.48 (0.3 to 0.79) | 0.004 |
| Age RA onset | 1.04 (1.02 to 1.06) | <0.001 | 1.04 (1.02 to 1.06) | <0.001 |
| Smoking, ever, baseline | 2.21 (1.21 to 4.03) | 0.01 | 1.91 (1.13 to 3.25) | 0.016 |
| Male gender | 1.44 (0.83 to 2.48) | 0.193 | 1.74 (1.05 to 2.86) | 0.03 |
| RF positive, baseline | 2.02 (1.07 to 3.82) | 0.029 | n.s. | |
| RA nodules, baseline | n.s. | 2.19 (1.08 to 4.41) | 0.029 | |
| Onset − OPD | 1.04 (1.00 to 1.07) | 0.027 | 1.03 (1.0 to 1.07) | 0.04 |
| Baseline major comorbidities* | 0.62 (0.40 to 0.95) | 0.027 | 0.67 (0.46 to 0.98) | 0.037 |
| Baseline ESR | - | n.s. | 1.01 (1.0 to 1.02) | 0.047 |
Onset − OPD: time from first RA symptoms to first hospital out patient appointment.
Note: variables not reported did not reach statistical significance in the respective models.
*Excluding respiratory.
csDMARD, conventional synthetic disease-modifying antirheumatic drugs; RA-ILD, rheumatoid arthritis interstitial lung disease; RF, rheumatoid factor.