Table 1 Description of the studied samples (N = 56,394)

Age (mean ± s.d.)

69.6 ± 11.7

74.4 ± 9.5

<0.001

Gender

Male

23,842 (43.3%)

658 (48.4%)

<0.001

Female

31,191 (56.7%)

703 (51.5%)

Race/ethnicity

Caucasian

40,554 (73.7%)

1,035 (76.1%)

<0.001

African American

5,356 (9.7%)

104 (7.6%)

Hispanic

1,331 (2.4%)

14 (1.0%)

American Indian

304 (0.6%)

2 (0.2%)

Asian

451 (0.8%)

19 (1.4%)

Other race

7,037 (12.8%)

187 (13.7%)

Insurance type

Medicare

40,130 (72.9%)

1,045 (76.8%)

<0.001

Medicaid

4,225 (7.7%)

49 (3.6%)

Managed care

5,742 (10.4%)

82 (6.0%)

Commercial

2,050 (3.7%)

77 (5.7%)

Other

1,056 (1.9%)

86 (6.3%)

Uninsured

1,830 (3.3%)

22 (1.6%)

Hospitals

Urban

46,212 (84.0%)

1,157 (85.0%)

0.301

Rural

8,821 (16.0%)

204 (15.0%)

Teaching

18,722 (34.0%)

467 (34.3%)

0.821

Non-teaching

36,311 (66.0%)

894 (65.7%)

Number of beds (mean ± s.d.)

398.1 ± 222.8

393.7 ± 215.9

0.465

LOS (mean ± s.d.)

4.7 ± 4.1

9.0 ± 9.2

<0.001

Number of discharges (mean ± s.d.)

1.2 ± 0.6

1.3 ± 0.8

<0.001

Admission type

Emergency

40,555 (73.7%)

906 (66.6%)

<0.001

Urgent

9,307 (17.0%)

236 (17.3%)

Elective

4,954 (9.0%)

213 (15.7%)

Trauma

217 (0.4%)

6 (0.4%)

ICU admission

4,521 (8.2%)

600 (44.1%)

<0.001

APR-DRG severity of illness

Minor

10,616 (19.3%)

67 (4.9%)

<0.001

Moderate

24,659 (44.8%)

218 (16.0%)

Major

17,176 (31.2%)

438 (32.2%)

Extreme

2,582 (4.7%)

638 (46.9%)

APR-DRG risk of mortality

Minor

20,979 (38.1%)

64 (4.7%)

<0.001

Moderate

21,900 (39.8%)

301 (22.1%)

Major

10,249 (18.6%)

476 (35.0%)

Extreme

1,905 (3.5%)

520 (38.2%)

Drug therapies

Oral/parenteral corticosteroids

46,990 (85.4%)

1,116 (82.0%)

<0.001

Antibiotics

48,132 (87.5%)

1,122 (82.4%)

<0.001

β-blockers

18,143 (33.0%)

448 (32.9%)

0.969

DCI score

0

22,614 (41.1%)

360 (26.5%)

<0.001

1

15,013 (27.3%)

373 (27.4%)

2

8,558 (15.6%)

250 (18.4%)

3

4,319 (7.9%)

156 (11.5%)

4+

4,529 (8.2%)

222 (16.3%)

Elixhauser comorbidity*

Valvular disease

1,027 (1.9%)

36 (2.7%)

0.037

Paralysis

119 (0.22%)

2 (0.2%)

0.803**

Neurological disorders

1,175 (2.1%)

32 (2.4%)

0.586

Other chronic lung disease

97 (0.2%)

17 (1.3%)

<0.001

Hypothyroidism

6,969 (12.7%)

143 (10.5%)

0.018

Renal failure

54 (0.1%)

8 (0.6%)

<0.001

AIDS

112 (0.2%)

2 (0.2%)

0.878**

Lymphoma

301 (0.6%)

13 (1.0%)

0.047

Metastatic cancer

756 (1.4%)

58 (4.3%)

<0.001

Solid tumor w/out metastasis

1,539 (2.8%)

82 (6.0%)

<0.001

Rheumatoid arthritis

169 (0.3%)

4 (0.3%)

1.000**

Weight loss

1,140 (2.1%)

139 (10.2%)

<0.001

Deficiency anemias

462 (0.8%)

9 (0.7%)

0.475

Psychoses

2,013 (3.7%)

39 (2.9%)

0.123

Depression

5,021 (9.1%)

92 (6.8%)

0.003