Decreased diffusion capacity on lung function testing in asymptomatic patients with systemic lupus erythematosus does not predict future lung disease

BackgroundIn a previous study performed 9 ± 3.6 years ago, 74 asymptomatic patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS) underwent lung function testing. A significantly low diffusion capacity (DLCO) ranging from 45% to 70% was recorded in 28 of the 74 (37.8%) patients who were all free of respiratory symptoms.AimThe aim of this report is to assess the clinical importance and the predictive value of a low DLCO in asymptomatic patients with SLE or APS.MethodsAsymptomatic patients with SLE and/or APS who were found to have a low DLCO in the previous study were contacted. Of the 28 patients, 15 were recruited and reevaluated in the current study (SLE with APS ( n = 7), SLE without APS ( n = 7); primary APS ( n = 1)). A full history, physical examination, nail bed capillaroscopy, current laboratory tests and full lung function tests including DLCO were performed.ResultsDuring a surveillance period of 9 ± 3.6 years, none of the patients developed lung disease. Diffusion capacity corrected for alveolar volume (DLCO/VA) improved in the study group during this period from 60.4% ± 7.0 to 76.1% ± 11.2 ( p ConclusionLow DLCO findings on lung function testing does not have a positive predictive value for the development of future lung disease in patients with SLE, with or without APS, who are free of respiratory symptoms. Our results suggest that a finding of low DLCO in asymptomatic patients with SLE, with or without APS, does not necessarily require further evaluation and imaging and may improve spontaneously over time. Further studies in a larger group of patients are needed to validate these findings.