Prevalence of respiratory function abnormalities in asymptomatic Chinese patients with juvenile onset systemic lupus erythematosus

Abstract

Objectives: To determine the prevalence and features of respiratory function alterations in asymptomatic Chinese patients with juvenile onset systemic erythematosus (JSLE) and to assess its relationship with clinical and immunological parameters. Methods: Twenty-two Chinese patients with JSLE followed up at our Rheumatology Clinic were recruited. Each underwent pulmonary function test (PFT) and completed a respiratory questionnaire. Four were excluded because of past history of pulmonary disease. Abnormal respiratory function findings if present would be correlated with the disease duration, disease activity, organ involvement, clinical features and immunological findings using multiple regression analysis. Results: All 18 patients analysed were totally free of pulmonary symptoms and disease. Thirteen patients (72%) had abnormal PFT results. Ten patients (56%) had decreased diffusion capacity of the lung (DLCO). Among them, 2 had restrictive lung pattern and one had mixed pattern while 7 had isolated DLCO impairment. Disease duration and renal involvement were both found to be significantly associated with decreased DLCO (p=0.037 and p=0.035 respectively). However, both factors became insignificant after multiple regression analysis. Neurological lupus was significantly associated with decreased FEF 25-75% and FEF 75% (p value 0.03 and p<0.001 respectively). Conclusion: Asymptomatic Chinese patients with JSLE and no prior pulmonary involvement showed frequent PFT abnormalities with decreased DLCO being the most common impairment. Neurological involvement was the only factor found to be significantly associated with abnormal lung function parameters. We speculate that decreased DLCO could be related to high occurrence of SLE-associated pulmonary hypertension in Chinese. Further in-depth evaluation and long term follow up study is warranted.