Objective Although several studies report a high incidence of lung manifestations in systemic lupus erythematosus (SLE), lung involvement is often underestimated in clinical practice. The objective of the work was to determine, in a large cohort of patients, the prevalence and clinical impact of different lung manifestations, their association with the autoantibody profile and describe the effectiveness of different therapeutic approaches in different clinical contexts.

Methods The study included patients with SLE, according to the ARA classification criteria of 1997 or EULAR/ACR of 2019, followed at the Lupus Clinic of the centers involved. Demographic data, disease characteristics, antibody profile, lung manifestations, cumulative damage and treatment were collected. The lung manifestations considered were: pleurisy, lupus pneumonia, pulmonary interstitial disease (ILD), alveolar hemorrhage, pulmonary embolism, pulmonary arterial hypertension and ‘shrinking lung’.

Results Of the 535 SLE patients included in the evaluation, 99 (18.5%) had at least one lung manifestation. The characteristics and distribution of lung involvement are shown in the table 1 (1). The most common was pleurisy, which appeared at the onset of the disease in most cases (56%). The residence of patients (urban areas versus rural areas) does not seem to have affected the risk of respiratory complications. In 61% of patients there was an increase of at least 1 point in the SLICC damage index (SDI) after the appearance of lung involvement. All patients were treated with corticosteroids. The evaluation of the effectiveness of immunosuppressive therapy was conditioned by the type of involvement: only half of patients with pleurisy received immunosuppression, mainly azathioprine, with 100% improvement, while 80% of ILD cases received immunosuppression, mainly mycophenolate mofetil, with a 50% response rate. Comparison of data from lung involvement patients, versus patients without, showed a significantly lower median age at onset of disease (p=0.002), higher male frequency (18% vs 9%; p=0.07), joint involvement (p=0.02) and constitutional symptoms (p=0.02). No difference was observed in the antibody profile.

Conclusions Our study confirms that, in addition to the known serositic involvement, other lung manifestations such ILD can occur with a relevant frequency and only in half of cases responds to immunosuppressive therapy.

The lower median age at the onset of the disease in these patients may likely be attributable to the high prevalence of pleurisy as a symptom of presentation. Consistent with the observation of increased morbidity in patients with respiratory disease, groups at greater risk of severe disease, such as males and early onset patients, were more represented in the group of patients with lung involvement.