Table 2.

Characteristics of non-surgical patients undergoing mechanical ventilation by annual hospital admission volume.

	Annual admission volume
Variable	<100	100–199	200–299	300–599	600+
Patients (n)	4,178	5,853	6,431	8,202	6,003
Age	68 ± 17	67 ± 17	65 ± 18	60 ± 18	60 ± 20
Female (%)	49	51	51	45	44
Race (%)
White	93	88	77	78	61
Black	4	7	19	15	26
Other	3	5	4	7	13
Admission Source (%)
ED	83	83	92	83	85
Direct	17	17	8	17	15
Charlson index
Mean	1.8 ± 1.6	1.8 ± 1.7	1.8 ±1.7	1.5 ± 1.6	1.6 ± 1.8
> 3 (%)	10	11	11	9	11
Primary diagnosis (%)
Respiratory	50	43	43	29	29
Cardiac	14	14	13	10	10
Neurological	7	8	9	21	22
Other	28	35	35	39	40
MedQual Probability of in-hospital death*	0.24	0.23	0.24	0.27	0.25
Distance from home to hospital (m)	4.3 [2.4 – 9.1]	3.6 [2.0 – 6.8]	3.2 [1.5 – 6.3]	5.2 [2.6 – 12.3]	4.6 [1.9 – 10.5]
Discharge location (%)
Home	24	23	25	34	34
Other hospital	18	13	11	6	5
SNF/LTAC	21	25	24	23	21
Dead	33	34	34	32	33
Other	5	5	6	6	7
30-day mortality	40.4	39.1	37.0	32.4	32.4

^*Available for 24,726 patients (81%)

ED = emergency department; SNF = skilled nursing facility; LTAC = long-term acute care