Table 3:

Adjusted Marginal Change in ED Length of Stay from Advanced Diagnostic Imaging^*

	Abdominal Pain		Chest Pain		Fever		Headache		Back Symptoms
	(n=3,521)		(n = 2,180)		(n = 2,026)		(n = 1,658)		(n = 1,451)
	Marginal Change	95% CI	Marginal Change	95% CI	Marginal Change	95% CI	Marginal Change	95% CI	Marginal Change	95% CI
GLM ϑ
	117.8	97.3 – 138.2	78.7	51.1 – 106.3	99.4	58.8 – 140.1	53.4	32.8 – 73.9	82.0	62.9 – 101.2
OLS ϑ
	119.3	97.5 – 141.1	80.8	47.5 – 114.1	123.6	72.9 – 174.3	47.5	25.3 – 69.7	80.6	60.0 – 101.3
Quantile ϑ
Q10	88.7	78.1 – 99.2	69.7	55.7 – 83.7	62.9	23.9 – 101.9	48.2	37.6 – 58.9	64.3	43.8 – 84.8
Q25	88.7	80.0 – 97.3	72.3	57.0 – 87.6	86.2	56.1 – 116.4	49.2	39.8 – 58.7	65.9	53.6 – 78.3
Q50	101.6	89.8 – 113.3	80.7	63.5 – 97.8	119.7	80.1 – 159.3	52.3	39.0 – 65.5	74.0	56.4 – 91.7
Q75	130.5	111.4 – 149.6	89.1	64.6 – 113.5	116.9	69.3 – 164.3	58.0	35.1 – 80.8	107.4	79.9 – 134.9
Q90	152.1	117.2 – 187.0	104.9	41.9 – 167.8	224.8	101.1 – 348.3	76.3	23.2 – 129.5	132.5	90.4 – 174.6

^*Each model is adjusted for patient age, gender, insurance, race/ethnicity, triage acuity, co-morbidities, provider type, geographic region, urbanicity, and hospital ownership.

^ϑSurvey-weighted estimates and 95% confidence intervals are presented for OLS and GLM models. Unweighted estimates and associated 95% confidence intervals based on bootstrapped analysis are presented for the quantile regression model.