Figure 2
From: Bidirectional association between asthma and migraines in adults: Two longitudinal follow-up studies
Schematic illustration of the participant selection process that was used in the present study. (a) Of a total of 1,125,691 participants, 113,059 asthma patients were matched with 113,059 control I participants by age group, sex, income group, region of residence, and past medical histories. (b) Of a total of 1,125,691 participants, 36,044 migraine patients were matched with 144,176 control II participants by age group, sex, income group, and region of residence.
