Figure 1

Figure 1 : 

Prevalence of airflow limitation (AL) according to the GOLD classification [16] and history of Chronic obstructive pulmonary disease (COPD).

CI: confidence interval; COPD: chronic obstructive pulmonary disease.

*AL: forced expiratory volume in one second (FEV1 )/forced vital capacity (FVC)<0.70.

**Screened AL: FEV1 /FVC<0.70 without known COPD.

***AL or history of COPD: FEV1 /FVC<0.70 or history of COPD (with FEV1 /FVC0.70).

I: stage I, mild AL (FEV1 /FVC<0.70 and predicted FEV1 80%).

II: stage II, moderate AL (FEV1 /FVC<0.70 and 50%predicted FEV1 <80%).

III: stage III, severe AL (FEV1 /FVC<0.70 and 30%predicted FEV1 <50%).

No stage IV was observed in the sample: very severe AL (FEV1 /FVC<0.70 and predicted FEV1 <30% or predicted FEV1 <50% plus chronic respiratory failure).