METHODS
In this case-control study, we recruited patients with SCD with or
without a physician diagnosis of asthma and healthy African American
controls between 6 and 18 years of age. Inclusion/exclusion
criteria: Inclusion criteria were a diagnosis of sickle cell disease
(HbSS, HbSβ-thalassemia+,
HbSβ-thalassemia0, HbSC, HbSO Arab) confirmed by
hemoglobin analysis. Age criteria was 6 to 18 years of age. Exclusion
criteria were preterm birth (born at < 37-week gestation) or
an inability to complete study activities. Participants completed study
activities only if they were at baseline health without respiratory or
SCD related complications occurring within the previous 4 weeks. Healthy
African American controls between the ages of 6 to 18 years were also
recruited but were excluded from the study for a diagnosis of asthma,
any episodes of wheezing leading to shortness of breath in the previous
12 months or presence of a bronchodilator response (≥ 12% increase in
FEV1 or FVC post-bronchodilator).
This study was approved by our institutional IRB and informed consent
and assent, where applicable, were obtained for all participants. A
thorough history was obtained, and a physical examination completed at
the time of study participation. A review of the participants’ medical
charts was conducted to obtain data regarding episodes of ACS, severe
pain crises requiring an inpatient stay, a physician-documented
diagnosis of asthma and other co-morbidities. All participants performed
pulmonary function tests (PFT) including MBW (Eco Medics Exhalyzer D,
software version 3.1.6) using nitrogen as the washout gas,
plethysmography (Morgan Scientific, ComPAS software version
1.10.2642.4440), and pre- and post- bronchodilator spirometry (Morgan
Scientific, ComPAS software version 1.10.2642.4440). Blood was obtained
from healthy controls at the time of the study visit as well as in those
SCD subjects with no laboratory studies in the previous 3 months