Background/Purpose: Rheumatoid Arthritis (RA) is a common autoimmune condition characterised by symmetrical inflammatory small joint polyarthropathy and loss of function. Systemic manifestations of RA are relatively common and thought to occur in upto 40% of patients. Interstitial lung disease (ILD) is a systemic complication of rheumatoid arthritis (RA) and is associated with significant increase in mortality compared to patients who do not have ILD. Idiopathic pulmonary fibrosis (IPF), previously known as cryptogenic fibrosing alveolitis, also has a poor prognosis, with median survival of 3-5 years from diagnosis in the era before any specific treatments were found³. More recently, there have been new treatment options for these patients with Perfenidone and Nindetanib licensed and NICE approved for treatment of IPF. Although it is believed that the prognosis of rheumatological ILD is better, there are not enough data on progression to able to confidently prognosticate these patients. The purpose of this study was to assess the differences in progression in patients with IPF compared to RAILD.

Methods: The Coventry ILD database was set up in 2011; all patients with ILD were added to this. This study retrospectively looked at the patients who had been entered in this registry. Other forms of ILD like Connective Tissue Disorder related ILD (CTD-ILD) were excluded from this study. Data were anonymised prior to extraction for the study and only data available prior to the use of Perfenidone and Nintedanib were utilised. Statistics were performed using R software which is freely downloadable from the internet.

Results: This study included 185 patients of which 55 had IPF and 37 had RAILD. As this is not a matched study, there are significant differences in the presentations of patients in the different arms. Table 1 illustrates the main differences in the study population. The mean age in the IPF group was 72.4 where as for RAILD the mean age was 65.7 with standard deviation of 9.1 and 9.6 respectively. This difference is statistically significant. FVC values were 84.7% and 95% operated and these differences were statistically significant. TLCO values were much lower in IPF patients with values of 48.2 compared with 61.5 in patients with RAILD. Univariate analysis revealed a number of variants including diagnosis, age, sex, TLCO; but multivariate analysis only showed TLCO as the significant variant. Median follow up was 41 months.

Table 1: Baseline characteristics demonstrating that RA has higher FVC at presentation.

Outcome:

Median 5 year survival was 48% for IPF and 81% for RAILD. Median 50% survival was 4.5 years for IPF and 9 years for RAILD.

Conclusion: Significant gaps remain in our understanding of the natural course of RAILD and IPF. Our study suggests that the biggest single factor influencing outcome is TLCO at baseline.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/progression-in-interstitial-lung-disease-comparison-of-rheumatoid-arthritis-with-idiopathic-pulmonary-fibrosis/