Background Pulmonary abnormalities can occur in childhood-onset systemic lupus erythematosus (cSLE) and affect both morbidity and mortality. The evaluation of cSLE patients by spirometry, carbon monoxide diffusing capacity (DLCO) and high-resolution computed chest tomography (HRCT) has been rarely reported. Furthermore, the concomitant evaluation of these pulmonary function tests with six-minute walk test (6MWT) and health related quality of life (HRQL) was not studied in pediatric lupus population.
Objectives To analyze the pulmonary function of cSLE patients and to identify possible correlations with the HRCT score, disease activity, disease cumulative damage and HRQL.
Methods Fifty-three cSLE patients of our University Hospital were invited to participate in this study. Patients were excluded at screening if they had acute pulmonary disease or were unable to perform the pulmonary function tests. Thirteen were excluded: 6 patients due to refuse to participate and 7 were not able to do the tests properly. Therefore, 40 patients were enrolled. They underwent spirometry and plethysmography. At study entry, demographic, clinical features, disease activity, disease damage, 6MWT, DLCO and HRCT were assessed. HRQL assessment was determined by the Portuguese version of generic instrument Pediatric Quality of Life Inventory 4.0 (PedsQL 4.0).
Results The mean age was 14.1 years (range 7.4-17.9). Subclinical abnormalities were evident in 19/40 (47%) cSLE patients according to spirometry/DLCO. Forced expired volume in one second (FEV1%) was the parameter most affected in 30%. The abnormal HRCT was evidenced in 22/30 patients (73%) and with mild abnormalities in 43%. Signs of airway affection were found in 50%. Twelve patients were hospitalized due to cSLE-related pulmonary complications before the study began. Total lung capacity (TLC%), vital capacity (VC%), forced vital capacity (FVC%), and FEV1% were significantly lower in cSLE patients who had been previously hospitalized due to pulmonary involvement compared to patients who had never been hospitalized (p<0.05). The HRCT-score was correlated with FEV1/VC (r=-0.63; p=0.0002), FEV1 (r=-0.54; p=0.018), FEF25-75% (r=-0.67; p<0.0001), and resistance (r=+0.49; p=0.0056). DLCO was also correlated with disease duration (r=+0.4; p=0.01). No correlations were found between lung function parameters or HRCT-score and disease activity, cumulative damage, current dose of all immunosuppressive agents, 6MWT, HRQL and functional ability scores (p>0.05).
Conclusions Almost half of patients with cSLE had subclinical abnormalities, regardless of the disease activity and disease cumulative damage. The positive correlation between duration of disease and DLCO was most likely related to improvement resulting from treatment. The cSLE-related pulmonary complications also determined functional damage.
Disclosure of Interest C. da Veiga: None declared, D. Coutinho: None declared, C. M. Nakaie: None declared, L. M. Campos: None declared, L. Suzuki: None declared, C. Leone: None declared, C. Silva Grant/research support from: Conselho Nacional de Desenvolvimento Científico e Tecnolόgico (CNPq 302724/2011-7 to CAS), Federico Foundation (to CAS) and by Núcleo de Apoio à Pesquisa “Saúde da Criança e do Adolescente” da USP (NAP-CriAd) to CAS., J. Rodrigues: None declared