Impact of pulmonary disease on patient-reported outcomes and patient-performed functional testing in systemic lupus erythematosus

Objectives This study examines the effect of pulmonary disease on patient-reported outcomes (PROs) and patient-performed outcome (PPO) in systemic lupus erythematosus (SLE) patients at a single tertiary referral center. Methods Pulmonary function tests (PFTs), chest imaging, SLE-related damage, and disease activity were examined in 110 SLE patients. Presence was noted of abnormal PFTs, pleural disease, pulmonary hypertension (PH), pulmonary infarction, interstitial lung disease (ILD), and shrinking lung syndrome (SLS). PROs included the Medical Outcome Short Form-36 Health Survey, Pittsburgh Sleep Quality Index, Fatigue Severity Scale, Borg Dyspnea Scale, patient dyspnea and cough. The PPO of interest was the six-minute walk test (6MWT). Relationships amongst PROs, 6MWT, and pulmonary disease were studied. Results Pulmonary disease was present in 62 (56%) of 110 subjects: 54 (49%) abnormal PFT, 13 (12%) pleural disease, 12 (11%) ILD, 11 (10%) SLS and five (5%) PH. Dyspnea was the only PRO found to be significantly associated with pulmonary disease (P=0.0004). Participants with pulmonary disease compared to those without had significantly reduced distance (P=0.00015, 95% CI for mean 39-125m) and predicted distance (P=0.00001, 10%-26%) on 6MWT. Conclusions Pulmonary disease is common in SLE and adversely impacts 6MWT distance and dyspnea without apparent influence on other PROs. The 6MWT may be a promising tool in the assessment of pulmonary disease in SLE.