PO:20:002 | Respiratory function tests predict bone mineral density in autoimmune rheumatic disease patients

Andrea Zoli¹, Panagiotis Garantziotis², Sebastian Böltz², Janina Auth², Sara Bayat², Jule Taubmann², Anna-Maria Liphardt², Maria Antonietta D'Agostino¹, Christina Bergmann², Georg Schett². | ¹Division of Rheumatology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Università Cattolica del Sacro Cuore, Roma, Italy; ²Department of Medicine 3, Rheumatology and Immunology, Friedrich Alexander Universität FAU, Erlangen, Germany.

Background. Several studies suggest that pulmonary function, especially in terms of vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1), directly correlate with physical activity and in particular with the 6-minute walk test (6MWT). In this perspective pulmonary function may be associated with bone health. Moreover, this relationship between lung function and bone might be exacerbated in AIDs patients who develop interstitial lung disease or require glucocorticoid therapy. High-resolution peripheral quantitative computed tomography (HRpQCT) is a sensitive technique to measure bone mass and microarchitecture in humans. We therefore sought to investigate the relationship between lung function test and bone mineral density in patients with autoimmune rheumatic diseases.

Methods. Patients affected by autoimmune rheumatic diseases were recruited from January to April 2025. Demographic data regarding age, gender, BMI, smoking habits, steroidal treatment, menopausal state, history of fracture and rheumatic disease were collected. HR-pQCT bone data from the distal radius and the tibia and pulmonary function test results were recorded. Pearson correlation test were performed between pulmonary function tests and HR-pQCT parameters of radius and tibia

Results. 28 patients affected by AIDs were enrolled: 3 (10,71%) with rheumatoid arthritis, 9 (32,14%) with systemic lupus erythematosus, 15 (53,57%) with scleroderma and 1 (3,57%) with idiopathic inflammatory myopathy. 11(39,29 %) patients were male with an average age of 47,64±13,77 years and an average BMI 25,22 ± 11,29 kg/m² . Among the patients, 14 (50%) had a history of smoking, 7 (29,17%) received glucocorticoid treatment and 8 (34.78%) had a history of fracture. Nine patients (32,14%) had confirmed interstitial lung disease. All the parameters calculated by HRpQCT in radius and tibia showed to positively correlate with the parameters of pulmonary function test [Table 1 and Table 2]. In particular the stronger association were between vital capacity, forced vital capacity and total lung capacity and the geometrical parameters of HRpQCT (total area, cortical perimeter, cortical area, trabecular area). Only the residual volume correlated inversely with the cortical BMD in both radius and tibia. Apparently, correlations were more frequent in radius than tibia.

Conclusion. This study suggests that impairment of pulmonary function is associated with bone loss in patients with autoimmune rheumatic diseases. Since pulmonary function is a major determinant for physical activity, its impact on bone loss is conceivable. To confirm these results a larger population with autoimmune rheumatic diseases is required to assess the interaction between lung function and bone health.