Prevalence of chronic obstructive pulmonary disease (COPD) defined by different criteria by age, and place of residence. The dark grey bar represents ‘rural’ participants and white bar represents ‘urban’ participants. Prevalence of chronic obstructive pulmonary disease (COPD) defined by different criteria by age, and place of residence. The dark grey bar represents ‘rural’ participants and white bar represents ‘urban’ participants. Om P Kurmi et al. BMJ Open Resp Res 2018;5:e000267 ©2018 by British Thoracic Society