Burden of obstructive lung disease study in Iran: First report of the prevalence and risk factors of COPD in five provinces

Background: Chronic obstructive pulmonary disease (COPD) is a global health burden that affects 300 million people worldwide. Globally, COPD was reported as the fourth leading cause of death in 2004 and is projected to occupy the third position in 2030. The goal of the present project is to describe the prevalence and determine the causes and risk factors of COPD in five provinces of Iran. Methods: This study followed a stratified cluster sampling strategy with proportional allocation within strata. The target population is all noninstitutionalized inhabitants, aged 18 and over, who inhabit in different provinces in Iran in the year 2017. The stratification of the sample according to the 31 provinces of Iran is incorporated in the sampling process. The core questionnaire was developed from preexisting validated questionnaires. The single most important outcome measure obtained as part of this protocol was spirometry before and after the administration of 200 mg (two puffs) of salbutamol. Results: The most commonly reported respiratory symptoms were as follows: wheezing (N=217, 20.4%, 95% confidence interval [CI]: 18%-22.8%), sputum production (N=173, 16.5%, 95% CI: 14.3%-18.8%), and dyspnea (N=131, 12.3%, 95% CI: 10.3%-14.3%). The overall COPD prevalence defined by the postbronchodilator spirometric Global Initiative for Chronic Obstructive Lung Disease criteria was 4.9%, higher in men (6.4%) than in women (3.9%). The prevalence of COPD was strongly dependent on smoking status, age, and sex. Conclusion: COPD is considered a preventable disease, and avoidance of exposure to major risk factors can prevent the vast majority of cases. The present study findings add to the literature on the prevalence of COPD in Iran and will help policy-makers, specialists, and all stakeholders to strategize and evaluate medical services required for reducing the prevalence of respiratory diseases. The data from our present study will serve as baseline information for future national and regional studies of COPD.