Table 1. Association between individual and institutional factors for probability of antibiotic prescription by classes among children with otitis media, national cohort, South Korea, 2012–2018.

Variables		No. (%)	Amoxicillin/amoxiclav	Cephalosporin	Macrolide
Age
	0–23 mon	16,125,174 (64.0)	0.97 (0.96–0.97)	0.85 (0.85–0.86)	1.10 (1.10–1.11)
	2–6 yr	9,087,090 (36.0)	1.00 (reference)	1.00 (reference)	1.00 (reference)
Sex
	Girl	11,775,515 (46.7)	1.00 (reference)	1.00 (reference)	1.00 (reference)
	Boy	13,436,749 (53.3)	0.98 (0.98–0.99)	1.04 (1.04–1.04)	1.02 (1.02–1.02)
Level of institution
	Primary	21,863,935 (86.7)	1.34 (1.33–1.34)	1.23 (1.22–1.243)	0.76 (0.75–0.76)
	Secondary	2,845,099 (11.3)	1.38 (1.37–1.38)	0.74 (0.73–0.75)	0.74 (0.73–0.74)
	Tertiary	503,230 (2.0)	1.00 (reference)	1.00 (reference)	1.00 (reference)
Location of institution
	Seoul capital area	13,530,134 (53.7)	1.00 (reference)	1.00 (reference)	1.00 (reference)
	Non-Seoul capital area	11,682,130 (46.3)	0.96 (0.95–0.96)	1.09 (1.08–1.093)	1.07 (1.06–1.07)
Acute otitis media
	AOM (suppurative)	10,293,497 (40.8)	1.00 (reference)	1.00 (reference)	1.00 (reference)
	OME	14,918,767 (59.2)	0.88 (0.87–0.88)	1.96 (1.95–1.97)	1.06 (1.05–1.06)
Period
	2012–2015	15,309,056 (60.7)	1.00 (reference)	1.00 (reference)	1.00 (reference)
	2016–2018	9,903,208 (39.3)	1.05 (1.04–1.05)	0.88 (0.87–0.88)	0.94 (0.93–0.94)

amoxiclav = amoxicillin-clavulanate, AOM = acute otitis media, OME = otitis media with effusion.