The Burden of Obstructive Lung Disease Initiative (BOLD): rationale and design.

Quantifying COPD prevalence worldwide is needed to document COPD's effect on disability, health care costs, and impaired quality of life and to inform governments and health planners. As an adjunct to data obtained from population-based studies, and for countries where a fully powered prevalence survey cannot be done, modeling of COPD prevalence and its economic burdens can help estimate potential health care needs and costs. For comparability, standardized methods for prevalence surveys are needed that can be used in countries at all levels of economic development. The Burden of Obstructive Lung Disease (BOLD) Initiative has developed a set of methods for estimating COPD prevalence and a model for assessing its economic impact, and piloted these methods in China and Turkey. The methods were revised to reflect the findings in the pilot studies, and BOLD is now making the standardized methods available worldwide. The BOLD Operations Center provides training, materials, quality control, and data analysis. BOLD emphasizes data quality control at every stage of the process. Data from paper forms completed in the field are entered electronically to a specially designed secure Web platform. Pre- and post-bronchodilator spirometry testing is done on all participants, and all spirometry data are reviewed for quality. Questionnaires are used to obtain information about respiratory symptoms, health status, exposure to risk factors, and economic data about the burden of COPD. BOLD's standardized methods will provide a uniform way to compare COPD burden within and between countries, and where differences are found, to explore explanations for these differences.