Rheumatoid arthritis-related interstitial lung disease (RA-ILD): a possible association between disease activity and prognosis

Objectives We hypothesized that RA disease activity might be associated with the survival of RA-ILD patients. To evaluate this possibility, we analyzed data on disease activity during follow-up in an RA-ILD cohort and compared disease activity between surviving patients and those who died during follow-up. Methods RA-ILD patients referred for medical evaluation and treatment at a single center, with CDAI scores during all follow up were included. We estimated the HR of the mean of the CDAI score during follow-up with survival. Also, we compared the survival function of patients with high disease activity (CDAI scores >= 22) during all follow-up with those with moderate and low disease activity. Results Thirty-seven patients were included. The mean of the CDAI score during follow-up was higher in death patients (median 30.8 +/- 18.5 Vs. 16.8 +/- 11.3), and a single unit increase in the mean of the CDAI score was associated with non-survival, HR:1.07 (95% CI: 1.02 -1.12). Patients with high disease activity during all follow-up (CDAI scores > 22) had lower survival function in comparison with moderate and low disease activity (P = 0.042). Conclusion The results of the study suggest that higher RA disease activity is associated with a worse prognosis of RA-ILD patients. The hypothesis that high disease activity is associated with worse survival in RA-ILD patients must be evaluated in more extensive cohort studies and clinical trials.