Is Obesity Associated with an Increased Risk for Airway Hyperresponsiveness and Development of Asthma?

We investigated the association between airway hyperresponsiveness (AHR) and obesity in adults referred for confirmation of asthma diagnosis. Data were analyzed for obesity class I (body mass index [BMI] 30-34.9 kg/m(2)), class II (BMI ≥ 35-39.9 kg/m(2)), and class III (BMI ≥ 40 kg/m(2)). Of 861 subjects, 401 demonstrated AHR; the mean dose of methacholine was 4.16 ± 2.55 mg/mL. A significant association between obesity and AHR was evident for all subjects: the odds ratio was 1.37 (95% CI 1.02-1.82; p = .0317). One unit of increased BMI (1 kg/m(2)) was associated with a 3.1% increase in AHR risk (95% CI 1.01-1.05, p < .005). The odds ratio increased from 1.86 (95% CI 1.27-1.76; p = .0012) for class I to 2.61 (95% CI 1.48-4.60; p = .0006) for class III. Obesity was found to be associated with AHR and appears to be a risk factor for asthma.