Airway hyperresponsiveness is negatively associated with obesity or overweight status in patients with asthma.
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 FEV(1) (PC(20)). 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 FEV(1) (l), FVC (l), and FEV(1)/FVC (%) in lung function tests. The prevalence of wheezing increased with higher BMI after adjustment for age, sex, smoking, medication history, and PC(20) (p < 0.0001). logPC(20) was lower in the normal weight group compared with the overweight group (p = 0.003). The risk of moderate or severe AHR (PC(20) ≤ 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.
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Jae-Woo
JW
Kwon
Sae-Hoon
SH
Kim
Tae-Bum
TB
Kim
Sang-Heon
SH
Kim
Heung-Woo
HW
Park
Yoon-Seok
YS
Chang
An-Soo
AS
Jang
You Sook
YS
Cho
Dong-Ho
DH
Nahm
Jung-Won
JW
Park
Ho Joo
HJ
Yoon
Young-Joo
YJ
Cho
Byoung Whui
BW
Choi
Hee-Bom
HB
Moon
Sang-Heon
SH
Cho
D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D015992:Body Mass Index; D016535:Bronchial Hyperreactivity / Q000150:complications* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000503:physiopathology*; D050177:Overweight / Q000150:complications* / Q000503:physiopathology*; D056910:Republic of Korea; D012129:Respiratory Function Tests; D012135:Respiratory Sounds; D012307:Risk Factors; D013851:Thinness / Q000150:complications / Q000503:physiopathology; D055815:Young Adult