Background: Interstitial lung disease (ILD) is the most common and serious organ manifestation in patients with inflammatory rheumatic disease (IRD). The clinical manifestations of ILD in IRD is very diverse and ranging from dyspnea, cough, sputum or sclerosiphonia to clubbing. However, there is also a group of patients who present no clinical symptoms of ILD, especially at initial diagnosis of IRD [1]. Until now, it is uncertain whether there is a difference of ILD in the context of lung function test and lung involvement, quantified by high resolution computed tomography (HRCT), between these two groups of IRD-ILD patients.

Objectives: The objective of this study is to quantify and analyse ILD between symptomatic and asymptomatic patients through measurement of radiologic features of ILD with artificial intelligence-based quantification of pulmonary HRCT (AIpqHRCT).

Methods: The study includes 67 patients (22 men and 45 women), mean age 57.2 ± 12.8 years at initial diagnosis of IRD and ILD with the following diseases: 62.7% (n=42) collagenosis, 34.3% (n=23) (poly)myositis and 3.0% (n=2) rheumatoid arthritis. No patient received an immunosuppressive (including glucocorticoids) or antifibrotic therapy. All patients received an HRCT of the lungs. The HRCT datasets were analysed by AIpqHRCT, using SATORI platform, regarding ground glass opacities (GGO), reticulations, volume, honey-combing and high attenuated volume (HAV). Furthermore, clinical data as well as lung function test were examined. All patients were divided into two groups concerning pulmonary symptoms: Asymptomatic group: no symptoms OR cough/ sputum without other symptoms OR dyspnea ≤ NYHA I without other symptoms or symptomatic group: sclerosiphonia OR dyspnea NYHA > I OR dyspnea NYHA I and cough/sputum.

Results: Asymptomatic group included 23 patients (34.3%) and the symptomatic group patients 44 patients (65.7%). There was no significant difference regarding age, gender, disease, smoking status or pack years between these groups. The analysis of the lung function test showed a significant higher FVC (forced vital capacity) and TLC (total lung capacity) in the asymptomatic group (FVC: 85.6 ± 17.4% and TLC: 84.5 ± 16.7%) versus the symptomatic group (FVC: 67.0 ± 15.5% and TLC: 73.1 ± 14.9%). Regarding DLCO (diffusion capacity of the lung for carbon monoxide) no significant difference was observed (asymptomatic group: 56.6 ± 18.1% versus symptomatic group: 50.1 ± 17.5%).

A comparison of the AIqpHRCT data revealed no significant difference in volume (asymptomatic group: 4.17 ± 1.4 liter versus symptomatic group: 3.92 ± 1.26 liter) and GGO (asymptomatic group: 8.75 ± 12.4% versus symptomatic group: 10.10 ± 8.49%). For reticulations (asymptomatic group: 2.34 ± 4.62% and symptomatic group: 5.49 ± 8.74%) and HAV (asymptomatic group: 10.10 ± 6.94% and symptomatic group: 14.90 ± 11.00%) a significant difference was observed. The AIqpHRCT sub-analysis of the 5 lobes of the lungs showed significant differences for the measured AIqpHRCT parameters.

Conclusion: This study highlights that one third of patients present no pulmonary symptoms at initial diagnosis of ILD in IRD. Asymptomatic patients presented significant higher FVC and TLC, whereas DLCO was decreased in both groups, highlighting DLCO as a screening parameter in IRD-ILD. Furthermore, it was shown that the morphological changes (reticulations and HAV), detectable on HRCT with AIqpHRCT, were significantly lower in asymptomatic patients. In summary, pulmonary asymptomatic patients can present an IRD-ILD and a consequent pulmonary screening should be performed to initiate an adequate therapy in the context of damage protection of the lungs.

Funding: Partially funded by the “Bundesministerium für Bildung und Forschung”, Germany (BMBF, FKZ: 01KX2021 and 01KX2121 as part of „Netzwerk Universitätsmedizin“ [NUM] 2.0).

REFERENCES: [1] Hoffmann T, Oelzner P, Franz M, Teichgräber U, Renz D, Förster M, et al. Assessing the diagnostic value of a potential screening tool for detecting early interstitial lung disease at the onset of inflammatory rheumatic diseases. Arthritis Res Ther. 2022;24(1):107.

Acknowledgements: NIL.

Disclosure of Interests: None declared.