Associations between airway hyperresponsiveness, obesity and lipoproteins in a longitudinal cohort

Background Epidemiological data have linked obesity with an increased risk of asthma, but the mechanisms responsible for this relationship remain unknown. One possible mechanism, which has received little attention, could be the effect of cholesterol metabolism on airway smooth muscle function. The present study investigated the association between airway hyperresponsiveness (AHR) to methacholine and body mass index (BMI) and plasma lipoproteins [low-density lipoprotein (LDL), high-density lipoprotein (HDL) and total cholesterol]. Methods Associations between AHR, BMI and plasma lipoproteins were assessed in a population-based cohort at ages 14 and 20 years. Results In unadjusted analyses, higher LDL cholesterol levels at age 14 were associated with AHR at age 20 in both sexes (P<0.05). HDL, LDL/HDL ratio and total cholesterol were not associated with AHR. In multiple regression analyses adjusted for sex, lung function, smoking and asthma, only higher levels of BMI at age 14 or 20 years were significantly associated with increased AHR at age 20 years, while neither LDL, HDL and LDL/HDL ratio nor total cholesterol were significantly associated with AHR. Conclusion We confirmed that in teenagers there is a strong association between BMI and AHR to methacholine. This association seems to be independent of the plasma lipoprotein levels at that age.