Deterioration of lung diffusion capacity during childhood in sickle cell disease

Abstract

Deterioration of lung diffusion capacity during childhood in sickle cell diseaseWord count: 1500To the Editor, The American Society of Hematology guidelines, 2019, recommended obtaining pulmonary function tests (PFTs) in patients with sickle cell disease (SCD) with various respiratory symptoms even if they are at their steady state. 1 These guidelines acknowledged that the usefulness of routine PFT is unknown because of the lack of research. However, this society further suggested that if the PFTs are obtained, it should be a comprehensive study including lung volumes and lung-diffusing capacity for carbon monoxyde (DLCO), in addition to spirometry. 1 A large study in adult patients (n=310) with SCD showed that pulmonary function is abnormal in 90% of adult patients with Hb-SS. 2 Common abnormalities included restrictive physiology and decreased DLCO. In this study, decreased DLCO indicated more severe sickle vasculopathy characterized by impaired hepatic and renal function, and a negative linear correlation existed between DLCO and age, suggesting that in adults with Hb-SS, disruption of alveolar-capillary gas exchange progressively deteriorated with time. 2 Two recent cross-sectional studies of children with SCD showed that pulmonary function, including DLCO, worsened with age and showed correlations with biological markers of inflammation (induced sputum IL-6 levels or blood neutrophilia). 3,4