Mortality rate in rheumatoid arthritis-related interstitial lung disease: the role of radiographic patterns

Background To assess mortality rate (MR) and standardized mortality rate (SMR) of rheumatoid arthritis-related interstitial lung disease (RA-ILD) patients and to evaluate the role of radiographic patterns in mortality. Methods A longitudinal multicentric study was conducted in RA-ILD patients from 2005 to 2015 and followed-up until October 2018 in Madrid. Patients were included in the Neumologia-Reumatología y Enfermedades Autoinmunes Registry, from diagnosis of ILD. The main outcome was all-cause mortality. The radiographic pattern at baseline [usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), or others] was the independent variable. Covariables included sociodemographic and clinical data. Survival techniques were used to estimate MR, expressed per 1000 persons-year with their 95% confidence intervals [CI]. Cox multiple regression model was run to examine the influence of radiographic patterns on survival. SMR [CI] was calculated comparing MR obtained with MR expected in the general population of Madrid by indirect age-gender standardization. Results 47 patients were included with a follow-up 242 patients-year. There were 16 (34%) deaths, and most frequent causes were acute ILD exacerbation and pneumonia. MR was 64.3 [39.4–104.9], and 50% of the patients died at 8.3 years from ILD diagnosis. After adjusting for confounders, (UIP compared to NSIP was associated with higher mortality risk. The overall SMR was 2.57 [1.4–4.17]. Women of 60–75 years of age were the group with the highest SMR. Conclusions RA-ILD is associated with an excess of mortality compared to general population. Our results support that UIP increases the risk of mortality in RA-ILD, regardless other factors.