Table 2.

Direct web access group: differences in frequency of occurrence of characteristics (n=5019)^*

Characteristic	Adjusted OR	p Value	95% CI	Marginal PHIE†	Marginal Pnon-HIE‡	Difference§
Hospitalized	0.271	<0.001	0.210 to 0.351	0.150	0.188	−191
Head CT	5.032	<0.001	3.074 to 8.236	0.019	0.004	74
Body CT	1.025	0.821	0.827 to 1.270	0.042	0.041	NS
Echocardiogram	1.858	0.407	0.430 to 8.027	0.001	0.000	NS
Outpatient Surgery	0.840	0.222	0.636 to 1.111	0.019	0.023	NS
Chest x-ray	4.367	<0.001	3.784 to 5.040	0.226	0.066	800
Laboratory tests	1.008	0.883	0.912 to 1.114	0.265	0.264	NS
24-h Admission	0.814	0.080	0.646 to 1.025	0.034	0.041	NS
Ankle x-ray	1.024	0.927	0.617 to 1.700	0.006	0.006	NS

^*Logistic regression analysis using generalized estimating equations (logit link function and binomial distribution); controlled for admission type, age, health plan status, logarithmic transformation of the Charlson comorbidity index and length of stay.

^†Marginal P_HIE = the mean probability of different healthcare procedures among HIE exposure patients.

^‡Marginal P_non-HIE = the mean probability of these procedures if patients with HIE exposure were not accessed by HIE.

^§Difference = (number of encounters from HIE exposure patients) × (marginal P_HIE−marginal P_non-HIE).

HIE, health information exchange; NS, non-significant.