Analysis of clinical–analytical characteristics in patients with rheumatoid arthritis and interstitial lung disease: Case–control study

Abstract

ObjectivesTo study the differences between rheumatoid arthritis (RA)-interstitial lung disease (ILD) patients and RA patients without ILD in severity markers and disease activity and to identify factors associated with the presence of ILD in RA patients. Patients and methodsPatients: RA-ILD patients selected from a multicentre cohort in Andalusia, Spain. Controls: RA-patients without ILD paired by sex, age and disease duration. Protocol: RA patients are reviewed every 3–6 months in rheumatology consultation. All patients are reviewed according to a predetermined protocol with systematic data collection. Outcomes: description of ILD type, differences in severity markers and disease activity in both groups. Other variables: ILD type by imaging technique (HRCT): nonspecific interstitial pneumonia (NSIP)/usual interstitial pneumonia (UIP). Lung function by PTF. Activity and severity markers of arthritis by DAS28-ESR, HAQ, RF, ACPA and erosions. Treatment with DMARD. Statistical analysis: descriptive and paired T-test or Chi-square test followed by binary logistic regression (DV: ILD in patients with RA). ResultsEighty-two patients were included, 41 RA-ILD and 41 RA controls. RF and ACPA positivity, serositis and osteoporosis were more frequent in RA-ILD patients. No significant differences in DAS28 were observed (P=.145) between RA-ILD and RA control patients. RA-ILD patients presented worse HAQ scores (P=.006). All patients were treated with disease modifying antirheumatic drugs (DMARDs). The risk of developing ILD in RA patients is tripled by a history of smoking or the presence of erosive arthritis (R2=.36). ConclusionsThe results of our study support the higher frequency of UIP and NSIP in RA patients. DLCO is the most sensitive parameter to detect ILD in RA patients. Our study showed that ILD in RA patients was associated with RA severity (presence of erosions and ACPA) and with a history of smoking.