Fig. 3: Flowchart of the selection of study subjects from the biennial NHANES survey cohorts.
From: Chronic comorbid conditions and asthma exacerbation occurrence in a general population sample
COPD chronic obstructive pulmonary disease. NHANES National Health and Nutrition Examination Survey. * self-reported asthma diagnosis based on question ‘Has a doctor ever told you that you have asthma?’ $ current asthma diagnosis based on question ‘Do you still have asthma?’.
