Investigating the potential associated factors and developing a risk model for interstitial lung disease in Chinese patients with systemic lupus erythematosus

Abstract

Objective: This study aimed to explore the risk factors for interstitial lung disease (ILD) in Chinese patients with systemic lupus erythematosus (SLE).

Patients and methods: This study recruited 40 SLE patients with ILD (SLE-ILD) and 40 SLE patients without ILD (SLE-non-ILD). Clinical data were collected from all patients, including basic clinical characteristics, affected organ systems, biochemical indexes, autoantibodies, and immunocytes.

Results: Compared with the SLE-non-ILD patients, SLE-ILD patients presented older age (p < 0.001), dry cough (p = 0.006), "velcro-like" crackles (p = 0.021), Raynaud's phenomenon (p = 0.040), elevated complement 3 (C3) level (p = 0.044), and lower SLE disease activity index score (p = 0.013) and cluster of difference-3 cell count (p = 0.043). Multivariate logistic regression analysis showed that older age (p < 0.001, odds ratio [OR]: 1.212), female sex (p = 0.022, OR: 37.075), renal involvement (p = 0.011, OR: 20.039), C3 level (p = 0.037, OR: 63.126), immunoglobulin (Ig) M level (p = 0.005, OR: 5.082), and positive anti-U1 small ribonucleoprotein antibody (anti-nRNP) result (p = 0.003, OR: 19.886) were independent ILD risk factors in SLE patients. Consequently, the ILD risk model in patients with SLE was constructed based on statistically significant variables from the multivariate logistic regression analysis, which significantly correlated with ILD risk, with an area under the curve of 0.887 (95% confidence interval: 0.815-0.960) using receiver operating characteristic curve analysis.

Conclusion: Age, female sex, renal involvement, C3 level, IgM level, and a positive anti-nRNP result are independent risk factors for ILD. Furthermore, their combination model is closely associated with an increased ILD risk in Chinese patients with SLE.

Keywords: Systemic lupus erythematosus; biochemical index; clinical features; interstitial lung disease; risk model.