Body Mass Index and Bronchodilator Responsiveness in Adults: Analysis of 2 Population-Based Studies in 4 South American Countries

Introduction: In South America, the rise in chronic respiratory diseases and weight-related issues due to the ongoing epidemiological transition has prompted research into their interrelationship. Methods: We sought to assess the association between body mass index (BMI) and bronchodilator responsiveness (BDR) among adults in Peru, Chile, Uruguay, and Argentina, using population-based data from 2 cohort studies. We defined BDR as a ≥12% and ≥200mL increase in either forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) after administration of a short-acting bronchodilator. The analysis also distinguished between FEV1-and FVC-specific BDR. We used logistic regression adjusted for confounders to evaluate associations with BMI. Results: Among 7160 participants (55.2% men, mean age 57.3 years), 23.7% had a BMI<25kg/m² and 35.5% had a BMI≥30 kg/m². Overall, 9.5% met the criteria for BDR; with 7.8% showing FEV1-specific and 4.9% FVC-specific responses. Compared to a BMI of 20–24.9kg/m², a BMI≥30kg/m² was associated with higher odds of FVC-specific BDR (adjusted odds ratio=1.47, 95% confidence interval 1.08–2.03), whereas a BMI<20kg/m² was associated with FEV1-specific BDR among participants with asthma (6.61, 1.23–35.6) and chronic bronchitis (4.71, 1.28–15.9), and with higher odds of any BDR in those with chronic bronchitis (3.90, 1.19–11.9). Conclusions: There was a differential relationship between BMI and types of BDR: higher BMI was associated with FVC-specific responsiveness, whereas lower BMI was linked to FEV1-specific BDR in individuals with asthma and chronic bronchitis and to overall BDR in those with chronic bronchitis.