The association of body mass index, weight gain and central obesity with activity-related breathlessness: The Swedish Cardiopulmonary Bioimage Study

Introduction: Breathlessness is common in the population, especially in women and associated with adverse health outcomes. Obesity (body mass index (BMI) >30 kg/m²) is rapidly increasing globally and its impact on breathlessness is unclear. Methods: This population-based study aimed primarily to evaluate the association of current BMI and self-reported change in BMI since age 20 with breathlessness (modified Research Council score ≥1) in the middle-aged population. Secondary aims were to evaluate factors that contribute to breathlessness in obesity, including the interaction with spirometric lung volume and sex. Results: We included 13 437 individuals; mean age 57.5 years; 52.5% women; mean BMI 26.8 (SD 4.3); mean BMI increase since age 20 was 5.0 kg/m²; and 1283 (9.6%) reported breathlessness. Obesity was strongly associated with increased breathlessness, OR 3.54 (95% CI, 3.03 to 4.13) independent of age, sex, smoking, airflow obstruction, exercise level and the presence of comorbidities. The association between BMI and breathlessness was modified by lung volume; the increase in breathlessness prevalence with higher BMI was steeper for individuals with lower forced vital capacity (FVC). The higher breathlessness prevalence in obese women than men (27.4% vs 12.5%; p<0.001) was related to their lower FVC. Irrespective of current BMI and confounders, individuals who had increased in BMI since age 20 had more breathlessness. Conclusion: Breathlessness is independently associated with obesity and with weight gain in adult life, and the association is stronger for individuals with lower lung volumes.