Association between subcutaneous abdominal fat and airway hyperresponsiveness

Epidemiological studies have shown that obesity is significantly associated with airway hyperresponsiveness (AHR). The aim of this study was to determine the effect of abdominal fat distribution on the prevalence of AHR. This study was conducted on subjects who visited the Seoul National University Hospital Gangnam Center from October 2003 to January 2009. Medical records of 3205 subjects who had both a methacholine bronchial provocation test and an abdominal CT scan were retrospectively reviewed. One hundred sixty-one subjects with AHR and their 161 controls were selected for the analysis. Total, subcutaneous, and visceral abdominal fat were objectively measured by an abdominal CT scan. Both body mass index (BMI) and waist circumference were significantly associated with AHR after adjustment for smoking (BMI: OR, 1.20; 95% confidence interval [CI], 1.07-1.35; waist circumference: OR, 1.07; 95% CI, 1.02-1.11). Total and subcutaneous abdominal fat increased the risk of AHR with an OR of 1.47 (95% CI, 1.08-2.02) in the case of total abdominal fat, and an OR of 1.99 (95% CI, 1.19-3.31) in the case of subcutaneous abdominal fat. However, visceral abdominal fat was not associated with AHR. The association between subcutaneous abdominal fat and AHR was consistent, especially in men. Subcutaneous abdominal fat was significantly associated with AHR, but visceral abdominal fat was not. These results suggest a possible role for subcutaneous fat on the later development of asthma.