Overweight and obesity as risk factors for impaired lung function in patients with asthma: A real-life experience

Several studies have outlined a possible relationship between an increased body mass index (BMI) and asthma. The aim of the study was to investigate in patients with asthma, enrolled in a real-life setting, a possible relationship between BMI and asthma parameters, including lung function markers (i.e., forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1], FEV1/FVC ratio, and forced expiratory flow at 25-75%), fractional concentration of exhaled nitric oxide (FeNO), asthma control level, Asthma Control Test (ACT), comorbid allergy, and allergic rhinitis (AR). The study included 286 patients with asthma. All subjects were evaluated performing clinical examination, spirometry, FeNO measurement, and ACT questionnaire. Ninety-six (33.6%) patients were overweight and 45 (14.1%) patients were obese. Lung function was significantly impaired in overweight and obese asthmatic patients in comparison with normal-weight ones. Increased BMI did not affect FeNO values and asthma control level. Overweight patients had double the risk (odds ratio [OR], 1.89) and obese patients had triple the risk (OR, 3.17) of having pathological FEV1 in comparison with normal-weight patients. Both in overweight (OR, 2.415) and obese patients (OR, 2.126), the risk to have pathological FEV1/FVC was about two times higher than in normal-weight patients. In overweight and obese asthmatic patients the probability of allergy was, respectively, 3.5 times (OR, 0.285) and 4.5 times (OR, 0.224) lower compared with normal-weight asthmatic patients. The risk of suffering from AR was three times lower in overweight (OR, 0.331) patients and six times lower in obese (OR, 0.163) patients. The present study suggests that BMI assessment should be routinely considered in asthmatic patients to reveal bronchial obstruction, also, in controlled asthma.