Table 1: Comorbidity groupings derived from comorbid conditions by principal components
analysis
Comorbidity groupings (principal components)*
Comorbid conditions†
Heart disease
Congestive heart failure
Cardiac arrhythmias
Valvular disease
Peripheral vascular disorders
Heart disease risk factors
Hypertension
Diabetes, uncomplicated
Diabetes, complicated
Neurological disease
Paralysis
Other neurological disorders
Respiratory disease
Pulmonary circulation disorders
Chronic pulmonary disease
Liver disease
Liver disease
Psychiatric disease
Alcohol abuse
Drug abuse
Psychoses
Depression
Coagulopathy
Coagulopathy
Renal disease
Renal failure
Anemia
Blood loss anemia
Deficiency anemias
Cancer
Lymphoma
Metastatic cancer
Solid tumor without metastases
Peptic ulcer disease
Peptic ulcer disease
1
Endocrine disease
Hypothyroidism
Rheumatological disease
Rheumatoid arthritis/collagen vascular
diseases
* Principal components analysis initially derived 9 comorbidity groupings. Groupings having
two or more clinically meaningful clusters of comorbid conditions were disaggregated so that
their final count was 13.
† The list of comorbid conditions comprised 26 out of 30 Elixhauser comorbidity measures (1).
2
Table 2: Characteristics of Veterans Affairs (VA) Intensive Care Unit (ICU) patients in the
study population with complete information on selected laboratory tests (n=182,792)
Explanatory variables
All
(n=182,792)
Died in hospital
Yes
No
(n=22,848)
(n=159,944)
11.2 (2.6)
9.6 (2.3)
11.4 (2.6)
66.2 (12.5)
70.5 (11.8)
65.6 (12.5)
177,966 (97.4)
22,440 (98.2)
155,526 (97.2)
White
116,335 (63.6)
14,055 (61.5)
102,280 (63.6)
Black
30,660 (16.8)
3,898 (17.1)
26,762 (16.7)
Others and unknown
35,797 (19.6)
4,895 (21.4)
30.902 (19.3)
134,121 (73.4)
11,479 (50.2)
122,642 (76.7)
4.9 (7.5)
8.4 (15.0)
4.4 (5.5)
43,013 (23.5)
6,638 (29.1)
36,375 (22.7)
1.8 (1.8)
2.3 (1.9)
1.7 (1.8)
Mean blood urea nitrogen level, mg/dL (SD)
29.4 (24.9)
42.9 (31.3)
27.5 (23.3)
Mean blood total white count, X109/L (SD)
10.5 (9.7)
14.3 (16.1)
10.0 (8.2)
Mean serum albumin level, g/dL (SD)
3.5 (0.8)
2.8 (0.9)
3.6 (0.7)
Mean hemoglobin level, g/dL (SD)
Demographic features
Mean age, years (SD)
Male, n (%)
Race, n (%)
ICU admission-related features
Direct admission, n (%)
Mean ICU length of stay, days (SD)
Chronic kidney disease, n (%)
Laboratory tests
Mean serum creatinine level, mg/dL (SD)
3
Comorbidity groupings, n (%)
Heart disease,
45,689 (25.0)
8,045 (35.2)
37,644 (23.5)
Heart disease risk factors
71,481 (39.1)
9,936 (43.5)
61,545 (38.5)
Neurological disease
13,341 (7.3)
2,163 (9.5)
11,178 (7.0)
Respiratory disease
38,307 (21.0)
6,097 (26.7)
32,210 (20.1)
9,426 (5.2)
1,709 (7.5)
7,717 (4.8)
37,798 (20.7)
4,535 (19.8)
33,263 (20.8)
Coagulopathy
7,127 (3.9)
1,727 (7.6)
5,400 (3.4)
Renal disease
12,902 (7.1)
2,427 (10.6)
10,475 (6.5)
Anemia
28,223 (15.4)
4,830 (21.1)
23,393 (14.6)
Cancer
19,430 (10.6)
4,070 (17.8)
15,360 (9.6)
Peptic ulcer disease
4,350 (2.4)
617 (2.7)
3,733 (2.3)
Endocrine disease
7,400 (4.0)
1,191 (5.2)
6,209 (3.9)
Rheumatological disease
2,406 (1.3)
399 (1.7)
2,007 (1.3)
Angina/unstable angina
4,602 (2.5)
48 (0.2)
4,554 (2.8)
Congestive heart failure
10,712 (5.9)
1,141 (5.0)
9,571 (6.0)
Arrhythmia
6,422 (3.5)
384 (1.7)
6,038 (3.8)
Acute myocardial infarction
18,487 (10.1)
1,620 (7.1)
16,867 (10.5)
Other cardiovascular diseases
23,592 (12.9)
960 (4.2)
22,632 (14.1)
Peripheral vascular disease
739 (0.4)
126 (0.6)
613 (0.4)
Valvular heart disease
723 (0.4)
72 (0.3)
651 (0.4)
Gastrointestinal bleeding
9,975 (5.5)
761 (3.3)
9,214 (5.8)
Other gastrointestinal disease
6,410 (3.5)
1,068 (4.7)
5,342 (3.3)
Gastrointestinal neoplasm
1,198 (0.7)
330 (1.4)
868 (0.5)
Serious neurological disease
6,263 (3.4)
1,204 (5.3)
5,059 (3.2)
Liver disease
Psychiatric disease
ICU Admission Diagnoses, n (%)
4
Minor neurological disease
407 (0.2)
28 (0.1)
379 (0.2)
51,639 (28.2)
5,370 (23.5)
46,269 (28.9)
Orthopedic, non-surgically treated
1,774 (1.0)
260 (1.1)
1,514 (0.9)
Renal disease
4,842 (2.6)
865 (3.8)
3,977 (2.5)
Lung neoplasm
1,402 (0.8)
582 (2.5)
820 (0.5)
Respiratory arrest/failure
7,897 (4.3)
2,776 (12.1)
5,121 (3.2)
Pneumonia
8,348 (4.6)
1,829 (8.0)
6,519 (4.1)
Chronic obstructive pulmonary disease
6,232 (3.4)
646 (2.8)
5,586 (3.5)
Other respiratory disease
3,082 (1.7)
497 (2.2)
2,585 (1.6)
Infection
8,046 (4.4)
2,281 (10.0)
5,765 (3.6)
25,382 (13.9)
5,344 (23.4)
20,038 (12.5)
Other medical diagnoses
Blood transfusion during first 30 days of ICU
admission, n (%)
5
Table 3: Logistic regression examining the relationship between blood transfusion and
hospital mortality in Veterans Affairs ICU admissions from years 2001 to 2005
Explanatory variable
Odds ratio (95% confidence interval)
Without selected
With selected blood
blood test variables
test variables
(n=258,826)
(n=182,792)
0.21 (0.18 to 0.25)
0.38 (0.32 to 0.46)
Age (per 10 years)
1.38 (1.36 to 1.39)
1.32 (1.31 to 1.34)
Male gender
1.45 (1.31 to 1.60)
1.27 (1.14 to 1.42)
Black
0.98 (0.94 to 1.02)
0.99 (0.95 to 1.03)
Others
1.27 (1.21 to 1.34)
1.30 (1.22 to 1.38)
Unknown
1.13 (1.08 to 1.17)
1.09 (1.04 to 1.15)
Direct Admission
0.50 (0.48 to 0.51)
0.60 (0.58 to 0.62)
Length of ICU stay (per day)
1.02 (1.02 to 1.02)
1.02 (1.02 to 1.02)
Hemoglobin (per g/dL)
0.79 (0.79 to 0.80)
0.87 (0.86 to 0.88)
Chronic kidney disease
1.04 (1.01 to 1.07)
0.99 (0.84 to 0.92)
Heart disease
1.09 (1.05 to 1.14)
1.13 (1.08 to 1.17)
Heart disease risk factors
0.83 (0.80 to 0.85)
0.84 (0.80 to 0.87)
Neurological disease
1.13 (1.07 to 1.19)
1.11 (1.04 to 1.17)
Respiratory disease
1.07 (1.04 to 1.11)
1.11 (1.06 to 1.15)
Liver disease
1.72 (1.62 to 1.82)
1.46 (1.36 to 1.57)
Psychiatric disease
1.02 (0.98 to 1.06)
1.01 (0.97 to 1.05)
Transfusion during first 30 days of ICU
admission
Race (Reference: White)
Comorbidity Groupings
6
Coagulopathy
1.68 (1.58 to 1.79)
1.60 (1.49 to 1.68)
Renal disease
1.15 (1.09 to 1.21)
0.95 (0.90 to 1.06)
Anemia
0.91 (0.88 to 0.95)
0.94 (0.89 to 0.98)
Peptic ulcer disease
1.03 (0.94 to 1.13)
1.05 (0.95 to 1.16)
Cancer
1.42 (1.36 to 1.48)
1.39 (1.34 to 1.45)
Endocrine disease
1.07 (1.01 to 1.14)
1.12 (1.04 to 1.20)
Rheumatological disease
1.07 (0.96 to 1.20)
1.07 (0.95 to 1.21)
ICU admission diagnoses (Reference: Other
medical diseases)
Angina/unstable angina
0.15 (0.12 to 0.20)
0.19 (0.14 to 0.27)
Congestive heart failure
1.00 (0.93 to 1.07)
0.93 (0.86 to 1.01)
Arrhythmia
0.57 (0.52 to 0.62)
0.63 (0.55 to 0.70)
Acute myocardial infarction
0.97 (0.91 to 1.03)
1.04 (0.97 to 1.12)
Other cardiovascular disease
0.91 (0.97 to 0.85)
0.63 (0.71 to 0.55)
Peripheral vascular disease
1.06 (0.89 to 1.27)
1.06 (0.86 to 1.31)
Valvular heart disease
0.70 (0.55 to 0.88)
0.81 (0.62 to 1.06)
Gastrointestinal bleeding
0.40 (0.37 to 0.43)
0.46 (0.42 to 0.51)
Other gastrointestinal disease
1.36 (1.27 to 1.46)
1.17 (1.08 to 1.26)
Gastrointestinal neoplasm
2.10 (1.86 to 2.36)
1.90 (1.65 to 2.18)
Serious neurological disease
2.48 (2.34 to 2.64)
2.64 (2.44 to 2.86)
Minor neurological disease
0.68 (0.46 to 1.01)
0.95 (0.63 to 1.45)
Orthopedic (medical)
0.81 (0.71 to 0.92)
0.85 (0.73 to 0.99)
Renal disease
1.30 (1.20 to 1.40)
0.76 (0.69 to 0.84)
Lung neoplasm
5.64 (5.10 to 6.23)
4.81 (4.22 to 5.47)
Respiratory arrest/failure
3.06 (2.92 to 3.22)
2.39 (2.25 to 2.53)
Pneumonia
1.84 (1.73 to 1.95)
1.45 (1.36 to 1.54)
7
1.28 (1.19 to 1.39)
1.31 (1.20 to 1.43)
Chronic obstructive pulmonary disease
1.52 (1.39 to 1.67)
1.36 (1.22 to 1.52)
Other respiratory disease
2.51 (2.39 to 2.64)
1.63 (1.54 to 1.73)
Blood urea nitrogen (mg/dL)
-
1.01 (1.01 to 1.01)
Blood total white blood cell (X109/L)
-
1.01 (1.01 to 1.01)
Serum albumin (g/dL)
-
0.53 (0.52 to -0.54)
Serum creatinine (mg/dL)
-
0.97 (0.96 to 0.98)
2001
1.22 (1.17 to 1.27)
1.06 (1.01 to 1.12)
2002
1.17 (1.13 to 1.22)
1.08 (1.03 to 1.14)
2003
1.11 (1.06 to 1.15)
1.05 (1.00 to 1.11)
2004
1.07 (1.03 to 1.12)
1.04 (0.99 to 1.09)
Hemoglobin level (per g/dL)
1.22 (1.20 to 1.25)
1.16 (1.14 to 1.19)
Heart disease
0.82 (0.76 to 0.88)
0.81 (0.75 to 0.88)
ICU admission for unstable angina
1.80 (0.98 to 3.39)
2.05 (0.97 to 4.35)
ICU admission for congestive heart failure
0.88 (0.73 to 1.05)
0.92 (0.75 to 1.14)
ICU admission for acute myocardial infarction
0.78 (0.69 to 0.88)
0.88 (0.76 to 1.02)
0.81
0.84
Infection
Other laboratory tests
Fiscal year (Reference: 2005)
Interaction of blood transfusion with
C-statistic for model
8
Table 4: Parameter estimates on the logit of hospital mortality for Hgb as a categorical
variable
Categorical variable for Hgb
Whole group (n=258,826)
Subset (n=182,792)
6.1 to 7.0
1.547
0.994
7.1 to 8.0
1.229
0.715
8.1 to 9.0
0.885
0.468
9.1 to 10.0
0.605
0.315
(reference: >10 g/dL)
9
Table 5: Parameter estimates on the logit of hospital mortality for the interaction of Hgb as a
categorical variable with transfusion receipt during first 30 days of ICU admission
Categorical variable for Hgb
Whole group (n=258,826)
Subset (n=182,792)
6.1 to 7.0
-1.505
-1.210
7.1 to 8.0
-1.230
-1.054
8.1 to 9.0
-1.058
-0.859
9.1 to 10.0
-0.854
-0.707
(reference: >10 g/dL)
10
Figure 1
Model-predicted probability of hospital mortality with and without
transfusion across nadir hemoglobin (Hgb) levels for subgroup of Veterans Affairs ICU
episodes with additional blood test results (n=182,792)
A. No comorbid heart disease admitted to ICU for reference medical diagnoses; B. Comorbid
heart disease admitted to ICU for reference medical diagnoses; C. Comorbid heart disease
admitted to ICU for acute myocardial infarction; For a 60-year old male transferred to ICU and
stayed for 30 days in fiscal year 2005. ICU = intensive care unit; black lines: no transfusion;
blue lines: transfusion; unbroken lines: point estimates; broken lines: 95% confidence limits.
11
Figure 2
Parameter estimates on the logit of hospital mortality for Hgb as a
categorical variable in regression models
A. Hgb category coefficients (reference: Hgb >10 g/dL); B. Hgb category*transfusion
interaction coefficients (reference: Hgb >10g/dL*transfusion).
12
Reference
1. Elixhauser A, Steiner C, Harris DR, Coffey RM. Comorbidity measures for use with
administrative data. Med Care. 1998;36(1):8-27.
13