. Author manuscript; available in PMC: 2021 Apr 1.

Published in final edited form as: Pediatrics. 2020 Mar 13;145(4):e20192989. doi: 10.1542/peds.2019-2989

Table 2.

Unadjusted annual change in referral rates by volume category and condition

	Asthma		Croup		Gastroenteritis
Volume Category	Annual change in referral odds (95% CI)	Interaction term^* (95% CI)	Annual change in referral odds (95% CI)	Interaction term^* (95% CI)	Annual change in referral odds (95% CI)	Interaction term^* (95% CI)
Lowest quartile	13.6 (5.6,22.2)	Ref	14.8 (2.6,28.3)	Ref	16.4 (3.5,31.0)	Ref
Quartile 2	12.2 (6.8,17.8)	1.0 (0.9,1.1)	22.3 (14.3,30.8)	1.1 (0.9,1.2)	20.3 (13.4,27.6)	1.0 (0.9,1.2)
Quartile 3	10.6 (5.8,15.7)	1.0 (0.9,1.1)	15.0 (4.2,26.8)	1.0 (0.9,1.2)	9.0 (0.6,18.0)	0.9 (0.8,1.1)
Highest quartile	9.1 (4.5,13.8)	1.0 (0.9,1.0)	11.9 (7.0,17.1)	1.0 (0.9,1.1)	9.2 (4.2,14.5)	0.9 (0.8,1.1)
Primarily Pediatric	0.8 (−17.7,23.5)	0.9 (0.7,1.1)	7.8 (−9.3,28.1)	1.0 (0.8,1.2)	1.5 (−12.7,18.1)	0.9 (0.7,1.1)

Assesses for difference in referral rate slopes compared with the lowest quartile