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 two cohort studies. We defined BDR as a ≥12% and ≥200 mL increase in either forced expiratory volume in one 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 7,160 participants (55.2% men, mean age 57.3 years), 23.7% had a BMI <25 kg/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 20-24.9 kg/m², a BMI ≥30 kg/m² was associated with higher odds of FVC-specific BDR (adjusted OR = 1.47, 95% CI 1.08-2.03), whereas a BMI <20 kg/m² was associated with FEV₁-specific BDR among participants with asthma (6.34, 1.16-35.1) and chronic bronchitis (4.71, 1.28-15.9), and with higher odds of any BDR in those with chronic bronchitis (3.90, 1.19-11.93).

Conclusion: 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.