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 (> or = 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 (PEF) (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/m2), normal (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), obesity (BMI, > or = 30 kg/m2), or morbid obesity (BMI, >34.9 kg/m2). 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.