title: Prevalence and etiological profile of chronic obstructive pulmonary disease in nonsmokers.
abstract: BACKGROUND
  Tobacco smoking has been recognized as the most important risk factor for chronic obstructive pulmonary disease (COPD) for a long time, but recent studies have shown that nonsmokers also contribute to a significant proportion of COPD. This study was performed to find out the proportion of nonsmoker individuals among COPD patients and to determine various etiologies in nonsmoker COPD patients.
  
  
  METHODS
  This study was an observational cross-sectional study conducted in Department of Pulmonary Medicine, MLN Medical College, Allahabad. A total of 200 COPD patients, aged >18 years of either gender with COPD, diagnosed by clinical and spirometric criteria (GOLD guideline) were included in the study.
  
  
  RESULTS
  Of the 200 COPD patients, the proportion of nonsmoker patients was 56.5%, and the smoker was 43.5%. Among 113 nonsmoker COPD patients, maximum number of patients (69.03%) belonged to low socioeconomic status but most important and statistically significant risk factor was exposure to biomass smoke (53.98%), other significant risk factors were treated pulmonary tuberculosis (32.74%), and long-standing asthma (14.16%). Risk factors that were not statistically significant were occupational exposure (9.73%), exposure to outdoor air pollution (3.54%), and lower respiratory tract infection during childhood (1.77%). The patients who were exposed to more than one risk factors, developed COPD at an earlier age.
  
  
  CONCLUSIONS
  This study revealed that nonsmokers contribute a significant proportion of COPD patients. Multiple risk factors other than smoking also play a major role in the development of COPD, particularly exposure to biomass smoke, treated pulmonary tuberculosis, and long-standing asthma.
authors.affiliation: Department of Pulmonary Medicine, Moti Lal Nehru Medical College, Allahabad, Uttar Pradesh, India.
authors.forename: Tariq
authors.initials: T
authors.lastname: Mahmood
authors.affiliation: Department of Pulmonary Medicine, Moti Lal Nehru Medical College, Allahabad, Uttar Pradesh, India.
authors.forename: Ravindra Kumar
authors.initials: RK
authors.lastname: Singh
authors.affiliation: Department of Pulmonary Medicine, KGMU, Lucknow, Uttar Pradesh, India.
authors.forename: Surya
authors.initials: S
authors.lastname: Kant
authors.affiliation: Department of Pulmonary Medicine, Moti Lal Nehru Medical College, Allahabad, Uttar Pradesh, India.
authors.forename: Amitabh Das
authors.initials: AD
authors.lastname: Shukla
authors.affiliation: Department of Pulmonary Medicine, Moti Lal Nehru Medical College, Allahabad, Uttar Pradesh, India.
authors.forename: Alok
authors.initials: A
authors.lastname: Chandra
authors.affiliation: Department of Pulmonary Medicine, Moti Lal Nehru Medical College, Allahabad, Uttar Pradesh, India.
authors.forename: Rajneesh Kumar
authors.initials: RK
authors.lastname: Srivastava
keywords: Chronic obstructive pulmonary disease; nonsmoker; risk factor; spirometry