Clinical Utility and Safety of Methacholine Challenge in Children with Sickle Cell Disease.

Introduction: Lung disease is major cause of morbidity in children with sickle cell disease (SCD), yet understanding of lung pathophysiology is lacking. The diagnosis of asthma in children with asthma has become an important consideration in clinical management because of its association with a twice greater the rate of painful and acute chest syndrome (ACS) episodes when compared to children without asthma. Provocation challenges with methacholine have been used in both clinical and research settings to evaluate the presence of degree of airway hyperresponsiveness (AHR) in studies of asthma; however, no such evaluation has been described in children with SCD.

Methods: As part of routine clinical care, 21 children with SCD multiple or severe acute chest syndrome (ACS) episodes were challenged with methacholine to determine if AHR was a component of their recurrent respiratory tract symptoms.

Results: A total of fourteen of the children had a positive challenge, none of whom had evidence of obstruction or bronchodilator reactivity on spirometry. Ten of fourteen patients were previously on inhaled corticosteroids and had their asthma diagnosis confirmed and four were given a new diagnosis of asthma. In each positive challenge, forced expiratory volume in one second reversed to at least 90% of baseline after bronchodilator treatment. No patient developed a painful or ACS episode temporally related to the challenge.

Conclusion: Evaluation of AHR with methacholine challenge in patients with SCD appears to be well tolerated and may elucidate the basis of lung morbidity in a subgroup of children with repetitive or serious ACS episodes.