Interstitial lung disease in patients with systemic lupus erythematosus: a cohort study

Abstract

Background/aim: Systemic lupus erythematosus (SLE) is an autoimmune disease with a variety of organ/system involvement. Respiratory system involvement is common in these patients and usually manifests itself by disorders of the lung parenchyma, pleura, pulmonary vasculature or diaphragm. In this study, we sought to determine the frequency of interstitial lung disease (ILD) in patients with SLE and associated risk factors. Materials and methods: Three hundred randomly chosen patients with SLE were included. Chest x-ray (CXR), lung spirometry and carbon monoxide diffusion test (DLCO) were performed. High-resolution thorax computed tomography (HRCT) was performed for a definite diagnosis of ILD. Results: Of 300 patients, 16% had ILD. At the start of the study, the prevalence obtained from the patients' records showed that 4% had ILD. The median age, mean duration of disease, and follow-up time were significantly higher and longer in patients with ILD compared to patients without (p < 0.05). Forced expiratory volume (FEV1), forced vital capacity (FVC), DLCO and total lung capacity (TLC) were significantly lower in patients with ILD (p < 0.001). Patients with ILD had a significantly higher frequency of arthritis, serositis, Raynaud's phenomenon, myositis, and anti-Scl70 positivity (p = 0.01, 0.001, 0.02, 0.004, and 0.001, respectively). A significantly higher number of patients had stopped using hydroxychloroquine (HCQ) in the ILD group (p = 0.04). Conclusion: ILD is common in patients with SLE. Spirometry, diffusion tests, and CXR are simple but valuable tools to diagnose ILD in patients with SLE. Considering the significant difference of prevalence between the start and the end of the study, one of the possibilities is the underrecognition of SLE-associated interstitial pulmonary disease. The higher administration of immunosuppressives in these patients may support a multisystemic active disease including the lungs.