Longitudinal Changes in Exercise Capacity in Children and Young Adults With Sickle Cell Anemia

Although the burden of sickle cell anemia (SCA) on affected individuals is significant, few
studies have examined the influence of having SCA on such measures of physical function as
exercise capacity. Moreover, the physiologic basis of poor physical functioning in children
with SCA is unknown and has not been studied extensively. The purpose of this proposal is to
use cardiopulmonary exercise testing (CPET) to gain a comprehensive understanding of
longitudinal changes in exercise capacity, and the effect of poor exercise capacity on
quality of life in children and young adults with SCA. The specific aims of this project are
to: 1) Measure peak oxygen consumption (VO2), the reference standard for exercise capacity,
in children and young adults with SCA classified by primary pathophysiologic contributor to
their decreased exercise capacity, and 2) compare results of this exercise test with the
results of previously completed exercise tests to determine longitudinal changes in exercise
capacity. These aims will be performed in 60 subjects with SCA and 30 matched controls who
participated in a previous study, IRB# 2009-13659; "The Physiologic Assessment of Exercise
Capacity in Pediatric Sickle Cell Anemia". In a secondary analysis, we will also study the
participants quality of life using a set of validated questionnaires. This study is
essential because it will address several areas of exercise capacity, including the longterm
effects of physiologic contributors to exercise limitation, that remain fundamental
knowledge gaps in SCA.

Inclusion Criteria:

1. age 8 to 21 years old; AND

2. Hb SS or S-β0 thalassemia disease, confirmed by hemoglobin analysis; AND

3. Previously participated in ClinicalTrials.gov ID: NCT01527799

Exclusion Criteria:

1. inability to perform maximal testing due to physical limitation (e.g. stroke or
avascular necrosis); OR

2. history of exercise-induced syncope or arrhythmias. Subjects will wait at least 2
weeks following any vaso-occlusive pain episode and 12 weeks following any
disease-related complication requiring transfusion support. Individuals on
hydroxyurea will be eligible. A total of 30 controls without SCA or sickle cell trait
will be matched for age, sex and race and recruited from the siblings, friends or
relatives of subjects enrolled on this study