Background/Purpose: Interstitial lung disease (ILD) is the most common extra-articular manifestation in Rheumatoid Arthritis (RA) generating higher mortality in these patients. The objective is to describe the mortality rate in a cohort of Rheumatoid Arthritis patients (RA) with Interstitial lung disease (ILD) over time, and to assess the influence of the ILD types on mortality risk.

Methods: The design was a longitudinal prospective study. A cohort of RA patients diagnosed of ILD since February 2007 until june 2017 were recruited and followed up in a multidisciplinary ILD, carried by a pneumologist and a rheumatologist in a Tertiary Hospital in Madrid, Spain. The main variable was death. Covariables: a) sociodemographic (age, sex), b) clinical (basal comorbidities, duration of RA disease, smoke, ILD type (non specific interstitial pneumonia [NSIP]; usual interstitial pneumonia [UIP]); c) pulmonary function tests (PTF ); d) laboratory tests (ESR, CRP, Rheumatoid factor) and therapy (concomitant corticoids, DMARDs and BA). Survival techniques were used to estimate the mortality rate (MR) in our cohort, expressed per 100 patient-years with their respective confidence interval [95 % CI]. They were follow-up until lost of follow-up, death or end of the study. Multivariable Cox proportional hazards model were run to evaluate the influence of ILD types on mortality.

Results: We included 37 patients, 67% were women with a mean lag time from RA diagnosis to ILD of 7.3±8 years and a mean age at diagnosis of ILD 69±9.6 years. 40% never smoked and the BMI was 27±4. Concomitant diseases were as follows: 62% hypertension, 13% cerebrovascular disease, 8% ischemic heart disease, 13% peripheral vascular disease 10% cancer, and 11% sleep apnea syndrome (SAS). Rheumatoid factor was positive in 92% of the patients, and the baseline ESR was 42± 22. Regarding the ILD type, 32% had NSIP and 65.6% had UIP. The mean values of PTF parameters were 102%±16.8 for FVC and 68%%±16.2 for DLCO. There were 7 deaths per 123.96 person-years at risk in the total cohort. The prevalence of deaths was 19%, and the most of them were due to respiratory cause (72%). The mean survival was 7.6 years and the MR was estimated in 5.6 [2.7-11.8] per 100 patient-years. MR for men 9.6 [3.1-29.9] and for women was 4.3[1.6-11.5]. Concerning the ILD types, MR for UIP was 10.2 [4.5-22.6] and for NSIP 2.0 [0.2-14]. All death people were RF positive and 72% smokers. Controlling for age, gender and smoking habit, the HR of mortality in IUP compared to NSIP was 5.4 [1.3-24.3].

Conclusion: 19% of the patients died, up to 72% were smokers and all of them positive to RF. The mortality rate in RA patients with ILD was 5.6% patient-years, with a mean survival time from diagnosis of ILD of 7.6 years. It seems that the type of ILD influence on mortality, showing that UIP patients have a poorer prognosis independently of the age and the sex.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-and-clinical-features-in-rheumatoid-arthritis-and-interstitial-lung-disease/