Background and objective: Obesity is an important factor in the development of asthma. Aspirin hypersensitivity affects 5-10% of asthmatics. The association between obesity and aspirin hypersensitivity in asthma is unclear. This study evaluated the association of BMI and asthma in patients with aspirin-tolerant asthma (ATA) and aspirin-intolerant asthma (AIA).
Methods: Aspirin provocation tests were performed in 667 asthmatic patients and changes in FEV(1) were used to categorize patients as ATA or AIA. The BMI of asthmatics was graded using the percentile BMI of 406 normal controls.
Results: Aspirin-induced changes in FEV(1)% ranged from 15% to 68%. Compared with the controls, the ATA group had a higher BMI (24.5 +/- 0.1 vs 23.8 +/- 0.2 kg/m(2), P = 0.001). The AIA group had a lower BMI. The aspirin-induced percentage fall in FEV(1) was inversely correlated with BMI in asthmatic patients (r = -0.094, P = 0.016). BMI was correlated with age and PC20, but not with FEV(1) in asthmatic patients. In a logistic regression adjusted for age, gender, and smoking status, FEV(1) and PC20 were associated with AIA with odds ratios of 0.986 and 0.586, respectively. BMI was associated with AIA with an odds ratio of 0.916.
Conclusions: Aspirin intolerance in asthmatics explains the lesser association with obesity. Obesity is not a risk factor in the development of asthma in patients with AIA.