Figure. Participant Enrollment Flow Diagram.

Of a total of 1 125 691 participants, 3819 of participants with peritonsillar abscesses were matched with 15 276 control participants by age group, sex, income group, region of residence, and past medical history. Those participants with peritonsillar abscess who could not be well matched were excluded. Then, the participants with peritonsillar abscesses and control participants were matched for meteorological data from 14, 10, 7, 5, and 3 days before the finding of peritonsillar abscess in the study group (index date) and the same data from the index date in the control group.