Lower airway obstruction is associated with increased morbidity in children with sickle cell disease

RATIONALE: The association between pulmonary function and morbidity in children with sickle cell disease (SCD) has not been previously evaluated. Our objective was to study the relationship between abnormalities in pulmonary function and morbidity as represented by the rate of hospitalizations for pain or acute chest syndrome (ACS) in children with SCD. METHODS: Results of pulmonary function tests obtained for clinical indications in children ages 6-18 years were classified as lower airway obstruction (forced expiratory volume in 1 sec/forced volume capacity <95% confidence interval adjusted for age, gender, race, and height), restriction (total lung capacity <80% predicted adjusted for gender, age, race, and height), and normal lung function. Incidence rates of pain or ACS were compared between children with lower airway obstruction or restriction and children with normal lung function. RESULTS: A total of 102 children, mean age at evaluation 12.0 years with follow-up of 3.8 years, were included. Children with lower airway obstruction had twice the rate of morbidity compared to children with normal lung function (2.5 vs. 1.2 hospitalizations for pain or ACS per patient-year, P = 0.003) (Risk ratio: 2.0; 95% CI: 1.3-3.3). Children with restriction did not have different rates of future morbidity compared to children with normal lung function (1.4 vs. 1.2 hospitalizations for pain or ACS per patient-year, P = 0.68) (Rate ratio: 1.1; 95% CI: 0.6-2.1). CONCLUSIONS: We conclude that children with SCD who have lower airway obstruction should have increased surveillance for future morbidity.