Association of lung function, chest radiographs and clinical features in infants with cystic fibrosis.

The optimal strategy for monitoring cystic fibrosis lung disease in infancy remains unclear. Our objective was to describe longitudinal associations between infant pulmonary function tests, chest radiograph scores and other characteristics. Cystic fibrosis patients aged ≤24 months were enrolled in a 10-centre study evaluating infant pulmonary function tests four times over a year. Chest radiographs ∼1 year apart were scored using the Wisconsin and Brasfield systems. Associations of infant pulmonary function tests with clinical characteristics were evaluated with mixed effects models. The 100 participants contributed 246 acceptable flow/volume (forced expiratory volume in 0.5 s (FEV0.5) and forced expiratory flow at 75% of the forced vital capacity (FEF75%)), 303 functional residual capacity measurements and 171 chest radiographs. Both Brasfield and Wisconsin chest radiograph scores worsened significantly over the 1-year interval. Worse Wisconsin chest radiograph scores and Staphylococcus aureus were both associated with hyperinflation (significantly increased functional residual capacity), but not with diminished FEV0.5 or FEF75%. Parent-reported cough was associated with significantly diminished forced expiratory flow at 75% but not with hyperinflation. In this infant cohort in whom we previously reported worsening in average lung function, chest radiograph scores also worsened over a year. The significant associations detected between both Wisconsin chest radiograph score and S. aureus and hyperinflation, as well as between cough and diminished flows, reinforce the ability of infant pulmonary function tests and chest radiographs to detect early cystic fibrosis lung disease.

Assessing the relationship between obesity and asthma in adolescent patients: a review.

The parallel rise in the prevalence of obesity and asthma over the last several decades has led to an extensive line of investigation into the relationship between these two conditions. This review will discuss evidence from laboratory-based studies, observational clinical studies, and clinical trials that suggests that obesity adversely influences asthma through multiple mechanisms. The effect of obesity on asthma during adolescence, including asthma incidence, the severity and control of existing asthma, lung function, and exacerbations, will be reviewed.

Lung function distinguishes preschool children with CF from healthy controls in a multi-center setting.

RATIONALE: Conducting clinical trials in cystic fibrosis (CF) preschoolers has been limited by lack of sensitive lung function measures performed across sites. OBJECTIVES: (1) Assess feasibility and short-term reproducibility of spirometry, forced oscillometry (FO), and inductance plethysmography (IP) in a multi-center preschool population; (2) compare ability of each technique to differentiate lung function of CF preschoolers and controls; (3) evaluate longitudinal changes in lung function; (4) estimate sample sizes for future trials. METHODS: A longitudinal, multi-center study of CF preschoolers was conducted utilizing standardized equipment, rigorous site training, and centralized lung function data review. CF subjects participated in up to four study visits 6 months apart, plus a 2-week reproducibility visit. Controls had one study visit. RESULTS: Ninety-three CF subjects and 87 controls participated. Acceptability rates were lowest for spirometry (55%) and highest for IP (77%). Spirometry success increased with age and having a prior acceptable measurement. FEV(1) , FEV(0.5) , and FEF(25-75) were lower for CF subjects than for controls; spirometric z-scores declined with age. IP measures of thoracoabdominal asynchrony were greater for CF subjects than for controls. FO indices did not distinguish CF from controls. FEV(1) and FEV(0.5) are able to detect the smallest treatment effect for a given sample size. CONCLUSIONS: Spirometry appears more sensitive than IP or FO for detecting lung disease in CF preschoolers; spirometric indices decline with age. Future trials using spirometry should include a run-in period for training and require acceptable data prior to enrollment. However, near-normal spirometric measurements in CF preschoolers may lead to difficulty detecting a treatment effect.

Sleep-disordered breathing is associated with asthma severity in children.

OBJECTIVE: To examine the relationships among obesity, sleep-disordered breathing (SDB, defined as intermittent nocturnal hypoxia and habitual snoring), and asthma severity in children. We hypothesized that obesity and SDB are associated with severe asthma at a 1- year follow-up. STUDY DESIGN: Children aged 4-18 years were recruited sequentially from a specialty asthma clinic and underwent physiological, anthropometric, and biochemical assessment at enrollment. Asthma severity was determined after 1 year of follow-up and guideline-based treatment, using a composite measure of level of controller medication, symptom burden, and health care utilization. Multivariate logistic regression was used to examine adjusted associations of SDB and obesity with asthma severity at 12-month follow-up. RESULTS: Among 108 subjects (mean age, 9.1±3.4 years; 45.4% African-American; 67.6% male), obesity and SDB were common, affecting 42.6% and 29.6% of subjects, respectively. After adjusting for obesity, race, and sex, children with SDB had a 3.62-fold increased odds of having severe asthma at follow-up (95% CI, 1.26-10.40). Obesity was not associated with asthma severity. CONCLUSION: SDB is a modifiable risk factor for severe asthma after 1 year of specialty asthma care. Further studies are needed to determine whether treating SDB improves asthma morbidity.

Multicenter evaluation of infant lung function tests as cystic fibrosis clinical trial endpoints.

RATIONALE: The conducting of clinical trials in infants with cystic fibrosis (CF) has been hindered by lack of sensitive outcome measures. OBJECTIVES: To evaluate safety, feasibility, and ability to detect abnormalities in lung function of serial pulmonary function tests (PFTs) in infants with CF. METHODS: Multicenter observational study using a commercial device, rigorous training, ongoing quality control, and over-reading of data by an independent panel. Raised volume rapid thoracoabdominal compression technique and plethysmography were performed at enrollment and at 6 and 12 months, with an additional 1-month reproducibility visit. MEASUREMENTS AND MAIN RESULTS: A total of 342 procedures were performed in 100 infants with CF at 10 centers. FRC measurements were acceptable at a higher proportion of study visits (89%) than raised volume (72%) or fractional lung volume (68%) measurements. Average Z scores for many parameters differed significantly from historical control values. Mean (95% confidence interval) Z scores were: -0.52 (-0.78 to -0.25) for forced expiratory flow at 75% (FEF75) for FVC; 1.92 (1.39-2.45) for FRC; 1.22 (0.68-1.76) for residual volume; 0.87 (0.60-1.13) for FRC/total lung capacity; and 0.66 (0.27-1.06) for residual volume/total lung capacity. For future multicenter clinical trials using infant PFTs as primary endpoints, minimum detectable treatment effects are presented for several sample sizes. CONCLUSIONS: In this 10-center study, key PFT measures were significantly different in infants with CF than in historical control subjects. However, infant PFTs do not yet appear ready as primary efficacy endpoints for multicenter clinical trials, particularly at inexperienced sites, based on acceptability rates, variability, and potentially large sample sizes required to detect reasonable treatment effects.

Obesity and obesity related co-morbidities in a referral population of children with asthma.

OBJECTIVE: Although there is mounting evidence that childhood obesity is a risk factor for incident asthma, it remains unclear if there is a distinct "asthma-obesity" phenotype. This study characterized body composition, obesity related co-morbidities, and traditional risk factors for asthma in a cohort of children referred for asthma management in a pulmonary clinic. We hypothesized that children with asthma and obesity would have distinct risk factors and co-morbidities, particularly with respect to metabolic and sleep abnormalities. PARTICIPANTS AND METHODS: One hundred sixteen asthmatic children ages 4-18 years underwent comprehensive measurements of common asthma risk factors as well as measurements of obesity-related morbidities, including lung function tests, atopy, and assessments of sleep (overnight oximetry and actigraphy), physical activity (accelerometry), and metabolism. Characteristics of children who were obese (BMI > or =95th percentile) were compared to those who were not obese (BMI <95th percentile). RESULTS: Obesity was present in 44% of participants. Obese participants had similar rates of atopy and family history of atopy, lung function, and asthma control at enrolment as their non-obese peers. A significantly higher proportion of obese participants had metabolic syndrome (23% vs. 0%) and habitual snoring (60% vs. 33%) compared to non-obese participants; insufficient sleep and nocturnal desaturations tended to be more prevalent among obese subjects. CONCLUSIONS: Obesity and obesity related co-morbidities were common in a referral population of children with asthma. The specific influence of metabolic abnormalities on asthma morbidity and management is still uncertain and likely will need to be addressed in prospective studies.

Beta 2 adrenergic receptor polymorphisms in cystic fibrosis.

There has been a recent emphasis on identifying modifier genes that influence the severity of cystic fibrosis (CF) lung disease. The beta-2-adrenergic receptor is expressed on airway smooth muscle, is the target for inhaled beta agonists, and has several common polymorphisms in its gene, ADRB2. Polymorphisms changing glycine to arginine or glutamate to glutamine in codons 16 and 27, respectively, were associated with differences in clinical response to inhaled beta agonists in individuals with asthma. We compared acute airway responsiveness and 5-year decline in pulmonary function in CF patients with different ADRB2 genotypes. One hundred and six subjects performed spirometry before and after the administration of an inhaled bronchodilator, and had ADRB2 genotype determined for codons 16 and 27. Comparing the percent change in FEV(1) and FEF(25-75) continuously revealed differences in the degree of airway responsiveness to bronchodilator between ADRB2-genotyped groups. However, there was no significant relationship between the ADRB2 genotype at positions 16 and 27 and bronchodilator response when defined as 12% improvement in FEV(1). Five-year decline in percent predicted FEV(1) showed no association with ADRB2 genotype. These data are consistent with variants of the ADRB2 gene having different responses to bronchodilator, but the long-term effects, if any, are not apparent over a 5-year period.