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Background: Systemic lupus erythematosus (SLE) is an autoimmune disease that potentially affects every organ. Pulmonary diseases (PD) are common among SLE patients and associated with an increased mortality and lower quality of life. PD in SLE can be categorized into subgroups including interstitial lung disease (ILD), pleural disease, airway related diseases, and shrinking lung syndrome (SLS). The prevalence of PD among newly diagnosed SLE patients has to our knowledge never been investigated. Symptoms of PD range from severe to non-specific and are often insidious of nature, why new diagnostic tools to detect SLE-related PD are warranted. Prior studies have shown that SLE patients often have reduced pulmonary function including reduced diffusion capacity often without presence of obvious pulmonary disease. Thoracic ultrasound (TUS) has shown to be a potential tool to detect ILD in patients with rheumatoid arthritis but has only been sparsely investigated in SLE. Further, one study has indicated that use of diaphragmatic ultrasound (DUS) may be able to detect a decreased pulmonary function in SLE.
Objectives: The primary objective was to describe the prevalence of PD and categories of PD among newly diagnosed SLE patients. The secondary objectives were among newly diagnosed SLE patients: i) to describe pulmonary function ii) explore if TUS and DUS are potential have tool to assess PD.
Methods: We included consecutively incident SLE patients diagnosed at the Department of Rheumatology, Odense University Hospital, in 2023-24. Participants were invited to a visit day approximately three months after their diagnosis. Inclusion criteria were age ≥ 18 years and fulfilment of the 2019 EULAR/ACR classification criteria. On a study day participants had:
Clinical examination including scoring of disease activity (SLEDAI-2K) and damage (SLICC/ACR DI)
Pulmonary function testing
Chest high-resolution computed tomography
TUS
DUS
At a multidisciplinary team discussion, involving rheumatologists, radiologists, and pulmonologists, participants were diagnosed with or without PD and categorised according to PD type.
Results: We included 10 patients, predominately white, six were females and mean age was 49 years (Table 1). Six patients were diagnosed with PD, among whom two had ILD and one SLS. Two participants had severely reduced ventilation- and diffusion capacity. TUS identified three patients with ≥ 10 B-lines, all with PD and two had ILD. One participant with SLS had markedly reduced diaphragmatic movement (Table 1).
Conclusion: PD was diagnosed in a substantial proportion of newly diagnosed SLE patients and in some cases, PD was of a severe nature. Decreased pulmonary function including reduced diffusion capacity was frequent, and in some instances without evident PD. We present the first series of TUS and DUS in newly diagnosed SLE patients. Increased numbers of B-lines were associated to PD with further reduced pulmonary function parameters measured as abnormally low ventilation- and diffusion capacity. In one patient a markedly decreased diaphragmatic movement was found compatible with SLS. The findings indicate that TUS and DUS have potential for identifying PD in SLE patients. However, this is a small series of patients, and the results need to be confirmed.
REFERENCES: NIL.
Baseline characteristics and pulmonary outcome measures of newly diagnosed SLE patients
| Patient number/ Outcome measure | Summarised, % or mean ± SD, (range) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Age at diagnosis, Years | 49 ± 16 (24-70) | 66 | 48 | 24 | 36 | 66 | 56 | 45 | 70 | 48 | 30 |
| Sex | 60% F | M | F | F | M | M | F | F | M | F | F |
| Race and ethnicity, white | 90% white | Yes | Yes | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Smoking status, Nev/Pri/Pre | Nev 60%
| Nev | Pre | Nev | Pri | Nev | Nev | Nev | Pri | Nev | Pre |
| DsDNA, ever positive Immunofluorescence | 50% | Pos | Neg | Pos | Pos | Neg | Pos | Pos | Neg | Neg | Neg |
| APL, ever positive | 30% | Pos | Neg | Neg | Pos | Neg | Pos | Neg | Neg | Neg | Neg |
| ACR/EULAR, score 0-51 | 22 ±
| 31 | 18 | 28 | 24 | 19 | 25 | 29 | 14 | 13 | 21 |
| SLEDAI-2K, score 0-105 | 5.4 ±
| 4 | 8 | 8 | 2 | 0 | 4 | 15 | 8 | 2 | 3 |
| Diagnosis of PD | 60% | PF and BE | TB and AT | None | None | ED and AT | Pl | SLS and PiFi | ILD and BE | None | None |
| FVC* | 94 ± 27 (39-120) | 102 | 91 | 107 | 116 | 98 | 51 | 39 | 120 | 104 | 111 |
| DLCO* | 71 ± 18 (37-90) | 89 | 81 | 80 | 78 | 64 | 44 | 37 | 90 | 73 | 69 |
| KCO* | 81 ± 9.7 (69-97) | 97 | 91 | 78 | 75 | 73 | 76 | 87 | 93 | 75 | 69 |
| B-lines (total number) | 7.7 | 6 | 6 | 1 | 4 | 8 | 10 | 17 | 14 | 8 | 3 |
| Diaphragmic discursion, cm** | 2.0 ± 1.0 (0.4-3.5) | 3.3 | 1.0 | 1.3 | 1.4 | 2.7 | 3.5 | 0.4 | 2.5 | 1.9 | 1.6 |
* % of expected value; ** normal value: > 1.4 cm for females and > 1.5 cm for males. F – Female; M – Male; Nev – Never; Pri – Prior; Pre – Present; dsDNA – anti-double stranded DNA; APL – anti-Phospholipid Antibodies, ever positive; ACR/EULAR - EULAR/ACR 2019 classification criteria; SLEDAI-2K - Systemic Lupus Erythematosus Disease Activity Index 2000; PD – Pulmonary disease; PF – Pleural fibrosis; BE – Bronchiectasis; TB – thickened bronchial wall; AT – atelectasis; ED – Elevated diaphragm; Pl – Pleuritis; SLS – Shrinking Lung Syndrome; PlFi – Pleuroparenchymateous Fibrosis; ILD - Interstitial Lung Disease; FVC – Forced Vital Capacity; DLCO - Diffusion Capacity for the Lung for Carbon Monoxide; KCO - Carbon Monoxide transfer Coefficient
Acknowledgements: We thank The Danish Rheumatism Association, Region Southern Denmark, Southern Danish University, Odense University Hospital, and A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal for Grants.
Disclosure of Interests: None declared.
© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (