Airway Hyperresponsiveness in Children With Sickle Cell Anemia

Background: The high prevalence of airway hyperresponsiveness (AHR) among children with sickle cell anemia (SCA) remains unexplained.Methods: To determine the relationship between AHR, features of asthma, and clinical characteristics of SCA, we conducted a multicenter, prospective cohort study of children with SCA. Dose response slope (DRS) was calculated to describe methacholine responsiveness, because 30% of participants did not achieve a 20% decrease in FEV1 after inhalation of the highest methacholine concentration, 25 mg/mL. Multiple linear regression analysis was done to identify independent predictors of DRS.Results: Methacholine challenge was performed in 99 children with SCA aged 5.6 to 19.9 years (median, 12.8 years). Fifty-four (55%) children had a provocative concentration of methacholine producing a 20% decrease in FEV1 < 4 mg/mL. In a multivariate analysis, independent associations were found between increased methacholine responsiveness and age (P < .001), IgE (P = .009), and lactate dehydrogenase (LDH) levels (P = .005). There was no association between methacholine responsiveness and a parent report of a doctor diagnosis of asthma (P = .986). Other characteristics of asthma were not associated with methacholine responsiveness, including positive skin tests to aeroallergens, exhaled nitric oxide, peripheral blood eosinophil count, and pulmonary function measures indicating airflow obstruction.Conclusions: In children with SCA, AHR to methacholine is prevalent. Younger age, serum IgE concentration, and LDH level, a marker of hemolysis, are associated with AHR. With the exception of serum IgE, no signs or symptoms of an allergic diathesis are associated with AHR. Although the relationship between methacholine responsiveness and LDH suggests that factors related to SCA may contribute to AHR, these results will need to be validated in future studies. CHEST 2011; 139(3):563-56

Obstructive sleep apnea and sickle cell anemia

OBJECTIVE: To ascertain the prevalence of and risk factors for obstructive sleep apnea syndrome (OSAS) in children with sickle cell anemia (SCA).METHODS: Cross-sectional baseline data were analyzed from the Sleep and Asthma Cohort Study, a multicenter prospective study designed to evaluate the contribution of sleep and breathing abnormalities to SCA-related morbidity in children ages 4 to 18 years, unselected for OSAS symptoms or asthma. Multivariable logistic regression assessed the relationships between OSAS status on the basis of overnight in-laboratory polysomnography and putative risk factors obtained from questionnaires and direct measurements.RESULTS: Participants included 243 children with a median age of 10 years; 50% were boys, 99% were of African heritage, and 95% were homozygous for β(S) hemoglobin. OSAS, defined by obstructive apnea hypopnea indices, was present in 100 (41%) or 25 (10%) children at cutpoints of ≥1 or ≥5, respectively. In univariate analyses, OSAS was associated with higher levels of habitual snoring, lower waking pulse oxygen saturation (Spo2), reduced lung function, less caretaker education, and non-preterm birth. Lower sleep-related Spo2 metrics were also associated with higher obstructive apnea hypopnea indices. In multivariable analyses, habitual snoring and lower waking Spo2 remained risk factors for OSAS in children with SCA.CONCLUSIONS: The prevalence of OSAS in children with SCA is higher than in the general pediatric population. Habitual snoring and lower waking Spo2 values, data easily obtained in routine care, were the strongest OSAS risk factors. Because OSAS is a treatable condition with adverse health outcomes, greater efforts are needed to screen, diagnose, and treat OSAS in this high-risk, vulnerable population.</p

Sleep Duration and Obesity among Adolescents Transitioning to Adulthood: Do Results Differ by Sex?

OBJECTIVES: To examine the association between short sleep duration and obesity among adolescents (mean age 16 years) transitioning into young adulthood (mean age 21 years) in the National Longitudinal Study of Adolescent Health (N=10,076). STUDY DESIGN: Self-reported sleep duration was categorized as <6, 6-8, or >8 hours. Obesity status, using measured height and weight, was defined as Body Mass Index (BMI) ≥95(th) percentile in adolescence and BMI ≥30 kg/m(2) in young adulthood. RESULTS: Cross-sectionally, short sleep duration was associated with obesity in adolescent males (Prevalence Ratio (PR) 1.8 [95% CI: 1.3, 2.4]) but not in females (PR 1.0 [95% CI: 0.7, 1.4]). In longitudinal analyses, short sleep duration in adolescence was associated with incident obesity in both males and females (Risk Ratio (RR) 1.2 [95% CI: 1.0, 1.6]) in young adulthood. No interactions by sex were noted. CONCLUSIONS: Analyzing the association of sleep duration and obesity longitudinally resolved sex discrepancies observed in earlier cross-sectional analyses. Optimizing sleep duration during adolescence may be an effective intervention to prevent excess weight gain in young adults