Bronchodilator Dose Responsiveness in Children and Adolescents: Clinical Features and Association with Future Asthma Exacerbations

BACKGROUND

Bronchodilator reversibility measures are often associated with poor asthma outcomes in children. Whether bronchodilator dose responsiveness is similarly useful in children is unclear.

OBJECTIVE

We hypothesized that children and adolescents requiring higher doses of bronchodilator to achieve maximal bronchodilation would have unique risk factors and increased risk of future exacerbation.

METHODS

Children (6-11 years, N = 299) and adolescents (12-21 years, N = 331) with confirmed asthma underwent clinical phenotyping procedures and a test of maximal bronchodilation with escalating doses of albuterol sulfate up to 720 mcg. Outcome measures were assessed at 12 months and included exacerbations treated with systemic corticosteroids, emergency department (ED) visits, and hospitalizations for asthma.

RESULTS

A total of 6.7% of children and 9.3% of adolescents had poor bronchodilator dose responsiveness, defined as attainment of maximal forced expiratory volume in 1 second with 720 mcg albuterol. Risk factors included type 2 inflammation, prior exacerbations, and greater asthma severity; historical pneumonia and tobacco exposure were also risk factors in children. Children and adolescents with poor bronchodilator dose responsiveness did not have increased current symptoms or impaired quality of life, but had approximately 2-fold increased odds of exacerbation or ED visit and approximately 3-fold increased odds of hospitalization by 12 months, independent of airflow obstruction.

CONCLUSIONS

Bronchodilator dose responsiveness may be useful for phenotyping and may be of utility in practice and future studies focused on asthma outcomes or quantification of treatment responses. In children and adolescents, this phenotype of poor bronchodilator responsiveness may be associated with periods of relatively stable disease yet marked airway constriction in response to triggers, including tobacco smoke, respiratory infections/pneumonia, and aeroallergens.

Anxiety Contributes to Poorer Asthma Outcomes in Inner-City Black Adolescents

BACKGROUND

The factors associated with poor asthma control, exacerbations, and health care utilization in black adolescents are complex and not well understood. Although psychological comorbidities such as anxiety are common in patients with asthma, these have not been studied in this population.

OBJECTIVE

This study characterized anxiety and associated asthma features in a cohort of black inner-city adolescents with persistent asthma and determined the association between anxiety symptoms, persistent uncontrolled asthma, and prospective health care utilization over 1 year.

METHODS

Eighty-six black adolescents were enrolled, phenotyped, and screened for anxiety symptoms with the Hospital Anxiety and Depression Scale anxiety subscale (HADS-A). Participants were telephoned every 2 months and a second study visit was completed at 1 year. Primary outcomes included persistent uncontrolled asthma, asthma exacerbations requiring systemic corticosteroids, and unscheduled health care utilization during the 1-year study period.

RESULTS

A total of 31% (n = 27) of adolescents had probable anxiety (ie, HADS-A score >7) and 27% (n = 23) had possible anxiety (ie, HADS-A score 5-7) at the baseline visit. Anxiety symptoms were associated with poorer asthma control, more impaired quality of life, and more insomnia symptoms. Adolescents with probable anxiety disorders also had increased odds of persistent uncontrolled asthma and emergency department utilization, with no differences in physician visits or systemic corticosteroid receipt.

CONCLUSIONS

Inner-city black adolescents with persistent asthma have a high prevalence of anxiety symptoms associated with poorer asthma control, impaired quality of life, insomnia, and increased prospective emergency department utilization for asthma. Routine screening for anxiety disorders may be useful in the clinical management of adolescents with asthma.

Predictors of emergency department use in children with persistent asthma in metropolitan Atlanta, Georgia

BACKGROUND

Racial disparities are evident among children with asthma in the United States, with non-Hispanic black children at particularly high risk for poor asthma outcomes, including frequent emergency department (ED) use for asthma exacerbations.

OBJECTIVE

To compare asthma features in non-Hispanic black vs white children in Atlanta, Georgia, and determine what clinical features predict future ED use for asthma.

METHODS

Self-reported black and white children 6 to 17 years of age with persistent asthma treated with controller medications completed medical history questionnaires, lung function testing, aeroallergen sensitization testing, and venipuncture. Medical records were reviewed for asthma-related ED visits for 12 months after the initial study visit.

RESULTS

A total of 276 children were enrolled. Black children, compared with white children, resided in more disadvantaged zip code areas and were more likely to have public insurance. Black children also had more features of asthma severity and more ED visits during the study period. Predictors of ED use, aside from a previous ED visit, differed by race. After adjustment for socioeconomic status, predictors of ED use in white children included an ED visit in the previous year and sensitization to pets and dust; in black children, predictors included ED use in the previous year, the number of asthma controller medications, forced expiratory volume in 1 second less than 80% predicted, blood eosinophil count greater than 4%, and mold sensitization.

CONCLUSION

Asthma features and ED use differ between black and white children in metropolitan Atlanta. Strategies to eliminate allergen exposure in the home and improve asthma control in these children may require tailoring for different racial groups.

An empirical study of the impact of complexity on participation in horserace betting

The aim of the research reported in this paper was to explore empirically whether levels of participation in horserace betting are affected by the complexity of the betting task. The study employed a systematic random sample of 1161 betting decisions made in UK offcourse betting offices during 1987. The research was conducted in a naturalistic setting where it was possible to grade complexity and to measure levels of participation. Complexity was defined in terms of both the number of alternatives in the decision-maker's choice set (number of horses in a race) and the complexity of the attributes set for each horserace (handicap vs. non-handicap races). Results indicated that bettors are not inhibited by alternative-based complexity, but may be inhibited to some extent by attribute-defined complexity.

Nutrient oxidation patterns and protein metabolism in lean and obese subjects

The immediate metabolic response to eating has been compared in a group of grossly obese subjects (W/H2 = 45) with that in lean controls (W/H2 = 22). Dietary intake of energy for obese subjects was based on their estimated basal energy expenditure for ideal body weight (given at an hourly rate of 3 X BMR over a 4-h period). Lean subjects were measured twice: control 1 with the same intake of energy as the obese in terms of ideal body weight and control 2 with the same energy intake in relation to each subject's measured resting energy expenditure (2.2 X REE). The changes in energy expenditure and nutrient disposal with the onset of eating have been assessed by a method of combined respiratory gas analysis and intravenous infusion of 13C-labelled leucine. Leucine kinetics were used to quantitate rapid changes in protein oxidation and to assess protein synthesis and degradation. 1) Total energy expenditure was 20-30 per cent greater in obese subjects than lean subjects in fasting and feeding. Energy expenditure expressed per kg fat-free mass, from D2O dilution, was similar in obese and lean subjects in both fasting (5.8 v. 5.5 kJ/kg FFM/h) and feeding [6.7 v. 6.3 (Control 2) kJ/kg FFM/h]. 2) The onset of eating was associated with increased carbohydrate and protein oxidation with decreased fat oxidation in both lean and obese individuals. In obese subjects, however, both the decrease in fat oxidation and the increase in protein oxidation were significantly smaller (P less than 0.05) than the corresponding increments in lean subjects (Control 2). 3) The rate of protein synthesis was significantly (P less than 0.05) higher in obese subjects both in the fasting state (99 v. 84 mumols leucine/kg FFM/h) and in the fed state [94 v. 67 (Control 2) mumols leucine/kg FFM/h]. The rate of protein degradation was also higher in obese individuals in fasting (117 +/- 6 v. 106 +/- 4 mumol leucine/kg FFM/h) and feeding [65 +/- 4 v. 54 +/- 6 (Control 2) mumol leucine/kg FFM/h] though these differences are not statistically significant (P greater than 0.05). 4) The observed differences between obese and lean individuals in protein and energy metabolism in the fasted state and in the immediate response to eating do not support a hypothesis of greater metabolic efficiency in obesity.

Spontaneous platelet aggregation in type IIB Tampa von Willebrand disease is inhibited by the 52/48-kDa fragment of normal von Willebrand factor, which contains the GPIb binding domain

The association of Type IIB von Willebrand disease (vWD) with chronic persistent thrombocytopenia and spontaneous platelet aggregation has recently been recognized. It has been shown that IIB von Willebrand factor (vWF) can initiate platelet aggregation by binding to the platelet glycoprotein (GP) lb receptor and inducing exposure of the GpIIb/IIIa fibrinogen receptor. In this study we demonstrate the increased binding of Type IIB Tampa vWF with normal platelets when compared with nonthrombocytopenic Type IIB vWF. Studies further demonstrate that spontaneous platelet aggregation initiated by IIB Tampa vWF can be blocked by a 52/48-kDa fragment of normal vWF, which contains the binding domain.

Inter-individual differences in fasting nutrient oxidation and the influence of diet composition

The pattern of fasting nutrient oxidation was measured in 11 healthy women of widely different body mass index by measurements of indirect calorimetry and urinary nitrogen excretion on 12 consecutive days. The women were given a diet of normal composition (44.5 per cent energy as carbohydrate; 40.7 per cent energy as fat) for 6 days and a high-carbohydrate diet (54.4 per cent energy as carbohydrate; 30.8 per cent energy as fat) for 6 days, in amounts designed to maintain energy balance for each woman. The differences in fasting respiratory quotient (RQ) between the women on the same diet were highly significant (P less than 0.001). The fasting RQ and the fasting carbohydrate and fat oxidation were significantly different between the two dietary periods, with the average difference in fasting RQ (0.027) being of similar magnitude to the difference in the food quotient (FQ) (0.026) between the two diets. The differences in fasting nutrient oxidation between individuals and between diets suggest differences in the extent of overnight carbohydrate storage as glycogen. There was no evidence that these differences were related to the tendency to gain weight in these subjects.