Table 3.

Differences in Community and Hospital Characteristics by Ambulance Service Level^a

Variable	BLS	Unweighted ALS	P Value	Weighted ALS
Zip Code Level, %
Household income/race/ethnicity groupb			<.001c
High/white	37	43		38
Low/white	7	8		7
High/black	2	1		2
Low/black	3	2		3
High/integrated	35	30		34
Low/integrated	16	16		16
Female sex	51	51	<.001	51
Age ≥65 y	14	14	.30	14
County Level, %
Metropolitand	87	85	.01	87
Persons with ≥4 y of college	24	23	<.001	24
General practice physicians	14	16	<.001	14
Any hospital with medical school affiliation	70	63	<.001	69
Hospital Level, %
Given aspirin at arrivale	98	98	.58	98
Given aspirin at dischargee	98	98	.63	98
Given β-blocker at dischargee	97	98	.003	98
Given evaluation for LVSDf	97	98	<.001	98
Given angiotensin-converting enzyme inhibitor or angiotensin receptor blocker for LVSDf	94	95	.05	95
Initial blood culture performed before first dose of antibioticsg	95	96	<.001	96
Given the most appropriate initial antibioticg	93	93	.01	93
Heart failure 30-d mortality rate	11	11	<.001	11
Myocardial infarction 30-d mortality rate	15	16	<.001	15
Pneumonia 30 d mortality rate	11	12	<.001	11

Abbreviations: ALS, advanced life support; BLS, basic life support; LVSD, left ventricular systolic dysfunction.

^aDifferences between BLS and unweighted ALS observations were tested for statistical significance using t test or χ² test, as appropriate. Because of missing data, some measures are based on less data than the full sample. Hospital-level measures are based on data from the Hospital Compare data sets.²⁵

^bThis was high if the median household income exceeded $40 000 (otherwise low) and predominantly black if more than 80% black, predominantly white if more than 80% white, and otherwise integrated.

^cχ² Test of independence was used for this categorical variable.

^dMetropolitan counties have at least 1 urbanized area of 50 000 or more population, and micropolitan counties have at least 1 urban cluster of at least 10 000 but less than 50 000 population. Both types have adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.

^eThe denominator for these measures is patients with myocardial infarction.

^fThe denominator for these measures is patients with heart failure.

^gThe denominator for these measures is patients with pneumonia.