Background/Purpose: Systemic Lupus Erythematosus (SLE) is an autoimmune disease that potentially affects any organ. Pulmonary diseases (PD) are common in SLE and cover several different subtypes including, interstitial lung diseases (ILD), shrinking lung syndrome (SLS), pleural and airway diseases. PD are associated with increased morbidity and mortality. The main purpose of this study is to determine the prevalence of PD and subtypes of PD in SLE and to identify predictors of PD.

Methods: In a cross-sectional study we identified all adult patients with SLE in Region Southern Denmark diagnosed and classified with SLE according to the 2019 EULAR/ACR classification criteria and invited eligible patients. Participants’ damage accrual was scored according to SLICC/ACR damage index.To diagnose PD, the participants underwent: High-resolution computed tomography scan of the thorax (HRCT)Pulmonary function tests (PFT) – body plethysmography, diffusion tests, and six-minute walk test (6MWT)PFT measures included: Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, total lung capacity (TLC), diffusing capacity of the lung for carbon monoxide (DLCO). Participants were diagnosed with or without PD and classified according to subtype. We investigated associations between PD and subtypes of PD and risk factors with first univariate analyses, then significant associations were analyzed with multivariable regression analyses.

Results: We invited 318 patients with SLE and 185 (58%) participated. Participants were predominantly white (94%), female (87%), with a mean age of 52 years (standard deviance 14), a median disease duration of 15 years (interquartile range 5.7 to 24), and 54% had ever smoked. PD were diagnosed in 59% of the participants, of which 12% had ILD, 1% SLS, 19% pleural diseases, and 38% airway diseases (Table 1).When predicting PD and subtypes of PD, ventilation parameters had low sensitivities ranging from 20% to 45%. DLCO was abnormal in 62% of all participants, including 46% of those without PD. Descriptions of HRCT scans were closely related to final diagnoses of PD, although some minor cystic changes and small nodules were insufficient to establish a diagnosis of PD. In univariate analyzes PD were significantly associated with decreased PFT measures such as decreased FEV1, FVC, TLC, and DLCO, but not with measures from 6MWT. In univariable analyzes both ILD and pleural diseases were significantly associated with decreased FEV1, FVC, TLC, and DLCO, while airway diseases associated with decreased FEV1, FEV1/FVC ratio, TLC, and DLCO. In multivariable logistic regression analyzes 12 variables had a significant association with PD or its subtypes (Table 2).

Conclusion: In a large, population-based study of PD in well-characterized patients with SLE, we identified PD in 59% of the cases. The most common manifestations were airway and pleural diseases, with ILD occurring in 12% of the patients. PFT alone contributed only to a limited extent to identification of patients with PD which was also true in multivariable analyzes. As PD are frequent and often treatable, diligent diagnosis is important.

Table 1. Prevalence of pulmonary diseases and subtypes of pulmonary diseases among 185 patients with Systemic Lupus Erythematosus. PD – Pulmonary Diseases, ILD – Interstitial Lung Diseases, UIP – Usual Interstitial Pneumonia, NSIP – Non-Specific Interstitial Pneumonia, HP – Hypersensitivity Pneumonitis, LIP – Lymphoid Interstitial Pneumonia; OP – Organizing Pneumonia, SLS – Shrinking Lung Syndrome; COPD – Chronic Obstructive Pulmonary Diseases, % is the percentage of the total study population.

Table 2. Prediction of any pulmonary disease and subtypes of pulmonary diseases in systemic lupus erythematosus by means of regression analyses. OR – Odds ratio, SDI – Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, SDI, no PD – Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index without score from pulmonary diseases, APS – Anti-Phospholipid Syndrome, DLCO – Diffusing Capacity of the Lung for Carbon Monoxide, % – percentages of expected, low* – less than 80% of expected, TLC – Total Lung Capacity.

« Back to ACR Convergence 2025

ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-and-predictors-of-types-and-subtypes-of-pulmonary-diseases-in-systemic-lupus-erythematosus-a-population-based-cross-sectional-study-using-high-resolution-computed-tomography-scan-and-pulmo/