Fig. 1.

Point prevalence of COPD in the whole population. The prevalence was calculated per 1000 persons and expressed with 95% confidence intervals, for three COPD definitions: previously diagnosed COPD (when self-reported by the respondent while completing the study questionnaire); COPD diagnosed by spirometry (confirmed by spirometry results based on GOLD Guidelines (2011), i.e. FEV₁/FVC <  0.70), and firstly diagnosed COPD by spirometry (when the respondent was diagnosed with COPD for the first time based on spirometry outcomes)