Understanding the determinants of health-related quality of life in rheumatoid arthritis-associated interstitial lung disease

Abstract

RationaleHealth-related quality of life (HRQL) is impaired among patients with interstitial lung disease (ILD). Little is understood about HRQL in specific subtypes of ILD. ObjectivesThe aim of this study was to characterize and identify clinical determinants of HRQL among patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) and compare them to patients with idiopathic pulmonary fibrosis (IPF). MethodsWe identified patients with a diagnosis of RA-ILD and IPF from an ongoing longitudinal cohort of ILD patients. HRQL was measured at their baseline visit using the Short Form Health Survey (SF-36), versions 1 and 2. Regression models were used to characterize and understand the relationship between selected baseline clinical covariates, the physical component score (PCS) and mental component score (MCS) of the SF-36. Measurements and main resultsRA-ILD patients (n = 50) were more likely to be younger and female compared to IPF patients (n = 50). After controlling for age and pulmonary function, RA-ILD patients had a lower HRQL compared to IPF patients, as measured by the PCS (P = 0.03), with significant differences in two of four PCS domains – bodily pain (P < 0.01) and general health (P = 0.01). Clinical covariates most strongly associated with a lower PCS in RA-ILD patients compared to IPF patients were the presence of joint pain or stiffness and dyspnea severity (P < 0.01). Mental and emotional health, as measured by the MCS, was similar between RA-ILD and IPF patients. ConclusionThe physical components of HRQL appear worse in RA-ILD patients compared to IPF patients as measured by the PCS of the SF-36. Differences in the PCS of the SF-36 can be explained in part by dyspnea severity and joint symptoms among patients with RA-ILD.