Increased body mass index does not lead to a worsening of asthma control in a large adult asthmatic population in Spain.

Background: Data on the association between obesity and asthma control are conflicting. We performed an analysis to elucidate the association between body mass index (BMI) and asthma control in a large sample of asthmatics. Materials and Methods: Data were obtained from a previous study in which the Asthma Control Questionnaire (ACQ) and Asthma Control Test (ACT) were validated for a Spanish population. The study sample comprised 607 adult (>= 18 years) asthmatic patients (61% female), of whom 235 (39%) had mild-persistent asthma, 246 (41%) had moderate-persistent asthma, and 126 (21%) had severe-persistent asthma. Results: The analysis showed a significant but very low correlation between BMI and ACQ-forced expiratory volume in the first second of expiration (FEV1) (r=0.1, P=.007) and ACQ-peak expiratory flow (PEE) (r=0.1, P=.010), but not ACQ-without lung function (wLF) (r=0.06, P=.116) or ACT. No significant association was found between BMI and asthma control as defined by physicians or according to ACT or ACQ (ACQ-FEV1, ACQ-PEF and ACQ-wLF) scores. We found no significant associations between ACT, ACQs (ACQ-FEV1, ACQ-PEF and ACQ-wLF), and BMI when BMI was classified as low (BMI, <18.5 kg/m(2)), normal (18.5-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), obesity (BMI, 30 kg/m(2)), or morbid obesity (BMI, >34.9 kg/m(2)). However, the percentage of patients with poor control was slightly greater in patients with low BMI and obesity. Conclusions: Using specific and validated tools, and in the context of clinical practice, this study did not find a relevant association between BMI and asthma control.