Association of body mass index with the development of methacholine airway hyperresponsiveness in men: the Normative Aging Study.
BACKGROUND
The rising prevalence of asthma in developed nations may be associated with the rising prevalence of obesity in these same nations. The relationship between body mass index (BMI) and the development of an objective marker for asthma, methacholine airway hyperresponsiveness (AHR), was investigated in adult men.


METHODS
Sixty one men who had no AHR at initial methacholine challenge testing but who developed AHR about 4 years later and 244 matched controls participated in the study. The effects of initial BMI and change in BMI on development of AHR were examined in conditional logistic regression models.


RESULTS
Initial BMI was found to have a non-linear relationship with development of AHR. Compared with men with initial BMI in the middle quintile, men with BMI in the lowest quintile (BMI=19.8-24.3 kg/m(2)) and those with BMI in the highest quintile (BMI >29.4 kg/m(2)) were more likely to develop AHR: OR=7.0 (95% CI 1.8 to 27.7) and OR=10.0 (95% CI 2.6 to 37.9), respectively. These results remained significant after controlling for age, smoking, IgE level, and initial FEV(1). In addition, there was a positive linear relationship between change in BMI over the period of observation and the subsequent development of AHR.


CONCLUSIONS
In this cohort of adult men, both a low BMI and a high BMI were associated with the development of AHR. For men with a low initial BMI the increased risk for development of AHR appears to be partly mediated by a gain in weight. The effect of BMI on AHR may suggest mechanisms in the observed associations between obesity and asthma.
Litonjua
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AA
Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. augusto.litonjua@channing.harvard.edu
Sparrow
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D
Celedon
J C
JC
DeMolles
D
D
Weiss
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ST
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015992:Body Mass Index; D001980:Bronchi / Q000187:drug effects*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D015331:Cohort Studies; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology*; D008875:Middle Aged; D012044:Regression Analysis; D014797:Vital Capacity / Q000187:drug effects
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride