Airway Hyperresponsiveness Is Negatively Associated with Obesity or Overweight Status in Patients with AsthmaKwon J.-W.a–c · Kim S.-H.a–c · Kim T.-B.d · Kim S.-H.e · Park H.-W.a, b · Chang Y.-S.a–c · Jang A.-S.f · Cho Y.S.d · Nahm D.-H.g · Park J.-W.h · Yoon H.J.e · Cho Y.-J.i · Choi B.W.j · Moon H.-B.d · Cho S.-H.a, b
aDepartment of Internal Medicine, Seoul National University College of Medicine and bInstitute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul, cDepartment of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, dDepartment of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, and eDepartment of Internal Medicine, Hanyang University College of Medicine, Seoul, fDepartment of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University School of Medicine, Bucheon, gDepartment of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, hDepartment of Internal Medicine, Yonsei University College of Medicine, iDepartment of Internal Medicine, Ewha Womans University College of Medicine, and jDepartment of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
Background: Obesity is a risk factor for asthma in the general population, but the effect of obesity on airway hyperresponsiveness (AFHR) or airway inflammation in asthma is not clear. This study evaluated the relationship between obesity and asthma, assessing aspects of symptoms, AHR, and severity. Methods: In total, 852 patients with asthma diagnosed by asthma specialists based on AHR as confirmed by a methacholine bronchial provocation test, were enrolled from the Cohort for Reality and Evolution of Adult Asthma in Korea (COREA) adult asthma cohort. The intensity of AHR was assessed by the concentration of methacholine needed to cause a 20% decrease in FEV1 (PC20). Patients were classified into four categories based on body mass index (BMI): underweight (<18.5), normal weight (18.5–24.9), overweight (25.0–29.9), and obese (≥30). Results: BMI was negatively correlated with FEV1 (l), FVC (l), and FEV1/FVC (%) in lung function tests. The prevalence of wheezing increased with higher BMI after adjustment for age, sex, smoking, medication history, and PC20 (p < 0.0001). logPC20 was lower in the normal weight group compared with the overweight group (p = 0.003). The risk of moderate or severe AHR (PC20 ≤ 4 mg/ml) decreased with increased BMI after adjustment for age, sex, smoking, and medication history (p = 0.035). Conclusions: Obesity is a risk factor for asthma in the general population, but obesity in asthmatic patients is negatively correlated with the intensity of AHR and is not related to asthma severity. Obesity is positively related with the prevalence of wheezing but negatively related to AHR in asthmatic patients.
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