Background: Dyspnoea is a common symptom in respiratory disease. However, data on its prevalence in general populations are limited and are mainly from high-income countries.

Aims: To estimate the dyspnoea prevalence across 41 sites of the BOLD study, and to investigate the risk factors for this respiratory symptom.

Methods: In the BOLD cross-sectional survey, dyspnoea was assessed in adults (?40 years) using the modified Medical Research Council (mMRC) dyspnoea scale. We estimated the prevalence of dyspnoea (mMRC score ?2) for each study site and compared its variation across countries and world regions. We used multivariable logistic regression to assess the association of dyspnoea with lung function parameters. This was conducted for each site and results were then pooled using random-effects meta-analysis.

Results: We included 25,806 participants in this study. Prevalence estimates for dyspnoea ranged from 0% in Mysore (India) to 28.8% in Nampicuan Talugtug (Philippines) with a mean prevalence of 13.7%. Dyspnoea prevalence varied widely across sites with unclear geographical pattern. Dyspnoea was strongly associated with both spirometric restriction (FVC<LLN: OR 2.07, 95%CI 1.75-2.45) and chronic airflow obstruction (FEV1/FVC<LLN: OR 3.76, 95%CI 1.04-4.65). These associations were not significantly different between sexes, age groups or smoking statuses. However, the association of dyspnoea with chronic airflow obstruction was significantly weaker among obese participants (OR 2.20, 95%CI 1.61-3.01).

Conclusion: There is a considerable variation in dyspnoea prevalence across the world, and the association of dyspnoea with airflow obstruction seems to be influenced by body mass.