Exhibit 4.

Regression Adjusted Mortality Rate Differences Between Black and White Patients When Both Experienced Ambulance Diversion at their Nearest Emergency Department (ED), Only Patients Nearby Black-Serving Hospitals, 2001–2011; SOURCE: Authors’ analysis of data from the California Office of Statewide Health Planning and Development

	Outcomes
	30-day mortality	90-day mortality	1-year mortality
Base rate (among patients in reference group)	11%	15%	22%
Diversion status (Reference group: nearest ED not on diversion on the day of admission)
Nearest ED’s exposure to diversion on the day of admission:
<6 hours	−0.53 [−1.98,0.92]	−0.29 [−1.76,1.18]	0.12 [−1.44,1.67]
[6–12) hours	0.13 [−1.61,1.88]	0.09 [−1.78,1.96]	0.02 [−1.91,1.95]
≥12 hours	−0.87 [−2.99,1.24]	−0.18 [−2.32,1.96]	−0.18 [−2.33,1.98]
Interaction between black patients and diversion level:
X low diversion (<6 hours)	−0.01 [−2.79,2.77]	−0.41 [−3.44,2.62]	0.00 [−3.91,3.91]
X medium diversion [6–12) hours	1.50 [−1.38,4.37]	3.16+ [−0.10,6.42]	5.02** [1.43,8.60]
X high diversion (≥ 12 hours)	2.25 [−0.64,5.13]	3.52* [0.55,6.49]	4.97** [1.36,8.59]
Control for tech access	Yes	Yes	Yes
Control for treatment	Yes	Yes	Yes
N	23323	23323	23323

^†Nearest ED based on Google Maps query of driving distance. Statistical significance indicates whether the coefficient is significantly different from zero based on the regression model.

⁺p<0.10

^*p<0.05

^**p<0.01