Obesity and Its Correlation With Spirometric Variables in Patients With Asthma

Alaa E. Ghabashi, MD; Mobeen Iqbal, MD, FCCP

In This Article

Abstract and Introduction


Background: The severity of bronchial asthma has been associated with increased body mass index (BMI) in several studies. We studied obesity in the asthmatic population and its possible correlation with spirometric variables.
Methods: We reviewed the medical records of 200 patients who underwent spirometry and were followed up in a pulmonary clinic for asthma. Ninety patients fulfilled the inclusion criteria. Patients were divided into Group І (forced expiratory volume in 1 second [FEV1] ≥ 80%, n = 64) and Group II (FEV1 60% to 79%, n = 26). Patients with BMI ≥ 30 were labeled as obese. In each group, correlates of BMI and forced expiratory flow, midexpiratory phase (FEF25%-75%) were analyzed with linear regression.
Results: The mean ages were 33.9 ± 13 years and 33.73 ± 10 years in Groups I and II, respectively. The mean BMI was 30.2 +/ 6 (Group I) and 30.36 ± 6 (Group II). BMI ≥ 30 was seen in 56.7% of patients in Group I and 53.3% in Group II. BMI did not correlate with spirometric variables in both groups. FEF25%-75% correlated with FEV1 and FEV1:forced vital capacity (FVC) in Group I (P = .003 and .0001, respectively) and FEV1:FVC in Group II (P = .0001). In Group 1, 38% of the patients had FEF25%-75% less than 80%.
Conclusion: Although obesity was prevalent in asthmatic patients, BMI did not correlate with any of the spirometric variables. A significant number of patients with normal FEV1 had impaired midflow rates that may reflect ongoing small airway inflammation.


Bronchial asthma and obesity are prevalent health problems worldwide.[1,2] Obesity has been associated with asthma in many studies, and several studies have reported a stronger correlation among women as compared with men.[3,4,5,6] The cause-and-effect relationship between asthma and obesity is still not clear, and scientific opinion remains divided.[7] No data demonstrate the relationship of small airway disease in asthmatics with obesity. The maximal forced expiratory flow, midexpiratory phase (FEF25%-75%), as a measure of small airway disease, has been shown to be a sensitive measure of airway obstruction and a predictor of airway hyperresponsiveness.[8,9,10,11] Moreover, it is common to find clinically stable asthmatic children with reduced values of FEF25%-75% and normal peak expiratory flow (PEF) and forced expiratory volume in 1 second (FEV1).[12]

On the basis of the above information, we aimed to study the prevalence of obesity in the asthmatic population and spirometric correlates of body mass index (BMI) and small airway function (FEF25%-75%). We also intended to study the prevalence of impaired midflow rates in the presence of normal FEV1 in our adult population.


Readers are encouraged to respond to George Lundberg, MD, Editor of MedGenMed, for the editor's eye only or for possible publication via email: glundberg@medscape.net


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.