POS0578 RISK AND RISK FACTORS OF MORTALITY IN RHEUMATOID ARTHRITIS PATIENTS WITH INTERSTITIAL LUNG DISEASE: A NATIONWIDE, POPULATION-BASED COHORT STUDY

Abstract

BackgroundRecent meta-analysis by Meihua Qiu et al [6] has shown ten factors associated with increased risk of mortality in rheumaoitd arthritis associated interstitial lung disease (RA-ILD): older age, male sex, smoking history, lower diffusing capacity of the lung for carbon monoxide, lower forced vital capacity predicted, higher composite physiological index, usual interstitial pneumonia pattern on high-resolution computed tomography, emphysema presence and acute exacerbation of ILD. However majority of the studies were single-centre studies. There were very limited studies on influence of treatment, especially disease-modifying anti-rheumatic drugs on mortality in RA-ILD.ObjectivesTo examine the risk and risk factors of mortality among RA patients with ILD.MethodsUsing the 1997-2013 Taiwanese National Health Insurance Research Database, we identified 32,289 newly diagnosed RA patients from 2001 to 2013. Of them, 214 subsequently developed ILD. We then matched RA patients with ILD at a ratio of 1:10 to RA patients without ILD by sex, age at RA diagnosis, year of RA diagnosis date and disease duration. We further conducted propensity score matching (PSM) at a 1:1 ratio for selected comorbidities using the greedy algorithm to select RA-ILD patients and controls. We examined the association of mortality with ILD in RA patients using the Cox proportional hazard model shown as adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs). Among 214 RA-ILD patients, we assessed factors associated with mortality using the multivariable Cox regression analysis.ResultsBefore PSM, a total of 164 RA-ILD patients and 1,640 RA patients without ILD were selected. After PSM, 155 RA-ILD patients and non-ILD RA controls were included. The incidences of mortality were 2,975 per 105 years and 2,981 per 105 years in the RA-ILD group before and after PSM, respectively. The incidence rate ratios (95% CIs) of mortality were 2.66 (1.95–3.63) and 2.55 (1.51–4.29) in the populations before and after PSM, respectively. Using the multivariable Cox regression analysis and the conditional Cox regression analysis, the risk of mortality was associated with ILD in RA patients (before PSM: aHR, 3.17 [2.17–4.63]; after PSM: 7.16 [1/76–29.15]). Among 214 RA-ILD patients, significant predictors for mortality included male gender (aHR, 2.59), age (aHR, 1.04), residence in suburban region (aHR, 2.29), peripheral vascular disease (PVD) (aHR, 83.26) and chronic pulmonary obstructive disease (COPD) (aHR, 2.73). The risk of mortality was not associated with use of non-steroidal anti-rheumatic drugs, corticosteroid, methotrexate, sulfasalazine, leflunomide, hydroxychloroquine, immunosuppressants, tumor necrosis factor inhibitors and rutixumab.ConclusionThis population-based, cohort study demonstrated that ILD was associated with increased risk of mortality in RA patients, and risk factors for mortality in RA-ILD patients included male, age, residence in suburban region, PVD and COPD. Use of DMARDs was not associated with the risk of mortality in RA-ILD patients.