Frequency and correlates of overweight status in adolescent asthma.

BACKGROUND: Debate exists within the literature concerning whether asthma and obesity are linked as comorbid conditions. Further study is required to understand the relationship between asthma and overweight status, and developmental considerations are an important priority area. OBJECTIVE: The present study addressed gaps in the existing literature by comparing rates of overweight status among a matched sample of adolescents with and without asthma and by examining correlates of overweight status among youth with asthma. METHODS: Rates and correlates of overweight status were compared among a matched cohort of 103 adolescents with asthma, 75 adolescents with asthma characterized by history of a severe acute event, and 92 normal controls. RESULTS: Significantly higher rates of overweight status were found among the asthma groups compared to the control group and to population estimates. Significant correlates for overweight status included younger age and earlier age at asthma diagnosis, suggesting that receiving an asthma diagnoses in early childhood may increase the propensity for weight gain. CONCLUSION: Asthma and obesity are problematic comorbid conditions, and specialized obesity prevention programs may be particularly necessary at the onset of a new asthma diagnosis. CLINICAL IMPLICATIONS: Identifying and addressing the factors that may contribute to the potential for obesity among youth with asthma are key research and clinical practice priorities.

Effect of body mass index on response to methacholine bronchial provocation in healthy and asthmatic adolescents.

A linkage between airway hyperreactivity and obesity could partly explain the prevalence of obesity in asthmatics. To test for such a linkage, we analyzed body mass index (BMI), pulmonary function, methacholine bronchial provocation, and asthma severity scores in 216 adolescents (aged 12-18 years), of whom 82 were healthy and 134 were asthmatic. Methacholine provocations in a subgroup of 36 subjects (healthy and asthmatic) enabled us to examine the effects of BMI on dynamic hyperinflation and ventilatory indices during induced bronchospasm. Age- and gender-specific BMI was higher in asthmatics (74 +/- 24%) compared to healthy subjects (61 +/- 28%, P < 0.002). General linear model analysis, in which baseline spirometric results were adjusted for gender, age, race, and height, showed opposing effects of BMI on expiratory flow in controls and asthmatics (P < 0.05), i.e., forced expired volume in 1 sec increased with BMI in controls (P < 0.02), but forced expiratory flow (FEF)(25-75%) decreased with BMI in asthmatics (P < 0.05). However, linear regression analysis showed no effect of BMI on the provocation dose for methacholine (PD(20)) in either controls or asthmatics, and there was no effect of BMI on asthma severity scores. Overweight (BMI >85th percentile) and nonoverweight subjects had similar degrees of dynamic hyperinflation during positive provocations, but overweight subjects had greater decreases in mean inspiratory flow (mean, 28% vs. 9%, P < 0.05). We conclude that our measurements support a relationship between overweight and baseline flow limitation, rather than a relationship between overweight and airways hyperreactivity, in the linkage between overweight and asthma during adolescence.