Asthma in Children with Sickle Cell Disease

Abstract

Sickle Cell Disease is a life-threatening hereditary blood disorder which affects millions of people worldwide. Pulmonary complications are important causes of morbidity and mortality in patients with sickle cell disease. Asthma is a recognised comorbidity of sickle cell disease and may occur in between 15 and 28% of children with sickle cell disease. It has been associated with increased episodes of acute chest syndrome and all cause mortality. Obstructive lung disease, however, is common in children with sickle cell disease, independent of an asthma diagnosis. This review explores the pathophysiology, diagnosis and therapeutic opportunities for asthma in sickle cell disease patients. The diagnostic challenges and inconsistencies in current clinical approaches are highlighted. Convergence of inflammatory pathways in sickle cell disease and asthma occurs, but there is also a heightened level of inflammation unique to sickle cell disease. Thus, wheezing may not be due to asthma but be a manifestation of sickle cell disease per se and the result of the increased pulmonary vascular volume. As a consequence, anti-asthma therapy may not be appropriate for all wheezy children with sickle cell disease and commencing treatment on the basis of a physician’s diagnosis alone is inappropriate. Data from paediatric cohorts suggest use of spirometry, aeroallergen sensitisation tests, impulse oscillometry and dedicated interdisciplinary pulmonary clinics could improve diagnosis accuracy. Corticosteroids and bronchodilators are well-established treatments for asthma; observational studies suggest they may provide benefit for some children with sickle cell disease, but therapies such as hydroxyurea may improve respiratory outcomes in others. It is, therefore, essential children are thoroughly investigated and followed-up and a personalised approach taken to their care. Prospective randomised studies are required to establish the effectiveness of asthma therapies in children with sickle cell disease.