Physiologic contributors to reduced exercise capacity in individuals with sickle cell anemia (SCA) are not well understood. The objective of this study was to characterize the cardiopulmonary response to maximal cardiopulmonary exercise testing (CPET) and determine factors associated with reduced exercise capacity among children and young adults with SCA. A cross-sectional cohort of 60 children and young adults (mean 15.1 ± 3.4 years) with hemoglobin SS or S/β0 thalassemia and 30 matched controls (mean 14.6 ± 3.5 years) without SCA or sickle cell trait underwent maximal CPET by a graded, symptom-limited cycle ergometry protocol with breath-by-breath, gas exchange analysis. Compared to controls without SCA, subjects with SCA demonstrated significantly lower peak VO2 (26.9 ± 6.9 vs. 37.0 ± 9.2 mL/kg/min, P < 0.001). Subjects demonstrated slower oxygen uptake (ΔVO2/ΔWR, 9 ± 2 vs. 12 ± 2 mL/min/watt, P < 0.001) and lower oxygen pulse (ΔVO2/ΔHR, 12 ± 4 vs. 20 ± 7 mL/beat, P < 0.001) as well as reduced oxygen uptake efficiency (ΔVE/ΔVO2, 42 ± 8 vs. 32 ± 5, P < 0.001) and ventilation efficiency (ΔVE/ΔVCO2, 30.3 ± 3.7 vs. 27.3 ± 2.5, P < 0.001) during CPET. Peak VO2 remained significantly lower in subjects with SCA after adjusting for age, sex, body mass index (BMI), and hemoglobin, which were independent predictors of peak VO2 for subjects with SCA. In the largest study to date using maximal CPET in SCA, we demonstrate that children and young adults with SCA have reduced exercise capacity attributable to factors independent of anemia. Complex derangements in gas exchange and oxygen uptake during maximal exercise are common in this population.
Background People with sickle cell disease (SCD) or sickle cell trait (SCT) may not have information about genetic inheritance needed for making informed reproductive health decisions. CHOICES is a web-based, multimedia educational intervention that provides information about reproductive options and consequences to help those with SCD or SCT identify and implement an informed parenting plan. Efficacy of CHOICES compared with usual care must be evaluated. Objective The purpose was to compare immediate posttest effects of CHOICES versus an attention control usual care intervention (e-Book) on SCD/SCT-related reproductive health knowledge, intention, and behavior. Methods In a randomized controlled study, we recruited subjects with SCD/SCT from clinics, community settings, and online networks with data collected at sites convenient to the 234 subjects with SCD (n = 136) or SCT (n = 98) (age ranged from18-35 years, 65% were female, and 94% were African American). Subjects completed a measure of sickle cell reproductive knowledge, intention, and behavior before and immediately after the intervention. Results Compared to the e-Book group, the CHOICES group had significantly higher average knowledge scores and probability of reporting a parenting plan to avoid SCD or SCD and SCT when pretest scores were controlled. Effects on intention and planned behavior were not significant. The CHOICES group showed significant change in their intention and planned behavior; the e-Book group did not show significant change in their intention, but their planned behavior differed significantly. Discussion Initial efficacy findings are encouraging but warrant planned booster sessions and outcome follow-ups to determine sustained intervention efficacy on reproductive health knowledge, intention, and actual behavior of persons with SCD/SCT.
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