Burden of Obstructive Lung Disease objectives

The Burden of Obstructive Lung Disease (BOLD) was designed to quantify the prevalence of obstructive lung disease and to identify its risk factors across several regions in the world. It was later extended to cover most of the world regions.

BOLD I collected baseline data on over 30,000 adults from 41 sites, mostly in low- and middle-income countries. BOLD II collected follow-up data of participants in 14 low- and middle-income sites and 4 North European sites.

BOLD I outcomes

  1. People in low-income regions of South Asia and Sub-Saharan Africa have smaller lungs than people in Europe
  2. Airflow obstruction is most strongly associated with tobacco use and is less common in low-income countries
  3. Other factors associated with obstruction of the airways include a history of tuberculosis, working in a dusty job, a low body weight and poor education
  4. Household air pollution does not explain the presence of chronic airflow obstruction in low- and middle-income countries.

BOLD II questions

  1. If the lungs of people in low-income regions are small, is this because they were born with small lungs or the lungs are being damaged by the local environment?
  2. If airflow obstruction is not common in low- and middle-income countries, why are mortality rates from COPD in those countries so high?
  3. Are the exposures associated with low lung function causing the problem or are they associated for some other reason?
  4. Can the link between poverty and poor lung function be explained?

BOLD sites