title: Burden of obstructive lung disease study in Tehran: Prevalence and risk factors of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) was ranked the sixth-most common cause of death worldwide in 1990, but now it is the third-most common cause. The goal of the present study was to assess the prevalence and determine the causes and risk factors of COPD in Tehran.
  
  
  METHODS
  This study followed a stratified cluster sampling strategy with proportional allocation within strata. The target population was all non-institutionalized inhabitants, aged 18 to 40 in one group and over 40 in another who resided in Tehran in 2013. The core questionnaire was developed from pre-existing validated questionnaires that had already been used in multi-national studies. 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: sputum production in 291 patients (16.2%) [95% confidence interval (CI): 14.5-17.9%], chronic cough in 171 (9.5%) (95% CI: 8.2-10.9%), wheezing in 377 (21.0%) (95%CI: 19.1-22.9%) and dyspnea in 388 patients (21.6%) (95% CI: 19.7-23.5%). The overall COPD prevalence defined by the post-bronchodilator spirometric functional criteria was 9.2%. This value in men (10.1%) was higher than in women (8.5%); the prevalence was significantly higher in subjects aged over 55 years (P ≤ 0.002). The prevalence of COPD was strongly dependent on smoking status, especially in ex-smokers, and increased considerably with age. 69% of patients with COPD were non-smoker.
  
  
  CONCLUSIONS
  The high prevalence of verified COPD, a great deal of which was undiagnosed before by a physician, highlights the necessity of raising awareness of this disease among health professionals, and use of spirometry in the primary care setting. A future cross-sectional and prospective cohort study should be performed to explore all risk factors and their impact on decline in lung function and worsening of respiratory symptoms especially in non-smokers.
authors.affiliation: Tobacco Prevention and Control Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hooman
authors.initials: H
authors.lastname: Sharifi
authors.affiliation: Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Masjedi
authors.affiliation: Tobacco Prevention and Control Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Habib
authors.initials: H
authors.lastname: Emami
authors.affiliation: Baqiyatallah Research Center of Gastroentrology and Liver diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Ghanei
authors.affiliation: Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Eslaminejad
authors.affiliation: Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Golnar
authors.initials: G
authors.lastname: Radmand
authors.affiliation: Oregon Health and Science University, Portland, Oregon, USA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Buist
keywords: Chronic obstructive pulmonary disease; Iran; prevalence