Longitudinal changes in lung function and somatic growth in children with sickle cell disease

Abstract

We studied the changes in the patterns of lung function and somatic growth over time in children and adolescents (10.6 +/- 3.5 years at first test) with hemoglobin SS (Hb-SS) sickle cell disease (SCD). Lung function and somatic growth were measured twice with an interval of 42.3 +/- 23.3 months in 45 children (25 females and 20 males) with Hb-SS SCD. The lung volumes slightly decreased but remained borderline normal in both tests. All spirometric indices were within the normal range but significantly decreased (P<0.001) at the time of the second test indicating development of lower airway obstruction (forced expiratory volume in the first second (FEV(1)): 87 +/- 21 vs. 80 +/- 15; FEV(1)/forced vital capacity (FVC): 89 +/- 7 vs. 85 +/- 6; FEF(25-75): 89 +/- 32 vs. 76 +/- 24). "Normal" pattern of lung function was initially found in 56% of the patients, but in only 29% in the second test. In contrast, those with "obstructive" pattern increased from 22 to 44%, and those with "restrictive" pattern from 22 to 27%. There was no association between history of asthma and pattern of lung function. "Normal" Body Mass Index (BMI) was found in 64% of the patients, whereas 13% had "High" BMI and 22% "Low" BMI. The two latter patterns were associated with abnormal lung function but only patients with normal BMI showed actual decline overtime. SCD is characterized by a predominantly obstructive pattern of lung function that increases in prevalence over time. There was no apparent causal relationship between the pattern of somatic growth and the pattern of lung function.