Fig. 1
From: Is atopy a risk indicator of chronic obstructive pulmonary disease in dairy farmers?
Flow chart of participants included in the study. Subjects were recruited through a screening program set up by two national health insurance organizations. Inclusion criteria in the screening programs were: men or women aged 40 to 74 years, with no history of chronic respiratory disease including asthma and hypersensitivity pneumonitis. Abbreviations: COPD: chronic obstructive lung disease; DF: dairy farmer; NF: non farmer