The impact of the implementation of electronic ordering on hospital pathology services

Diagnosis-related Groups (DRG)

Page last updated: 15 May 2013

Assessing test types and volume by matched diagnosis-related groups (DRGs) allows analyses to control for the variability of test ordering between different categories as a means of examining patterns and variations of pathology ordering.4 38 A comparison of the mean number of tests per admission and mean length of stay, between the four years, for the top-10 DRGs based on pathology utilisation, is shown in Table 11. When comparing the period before electronic ordering was available (2008) with the period after it was available and well-established (2011), the pattern of results was inconsistent. Some DRGs showed an increase in the number of tests per patient admission, for example G02A (Major bowel procedure) showed a considerable increase from a mean of 76.11 to 91.88 tests per patient admission, whereas other DRGs (e.g., A06B [Tracheostomy]) showed a reduction in the mean tests per patient admission. Similarly, mean length of stay was reduced over time for DRGs such as E65B (Chronic Obstructive Airways Disease) but increased for F62B (Heart Failure & Shock). Conversely, the consistency in test volumes and length of stay for L61Z (Haemodialysis) is what would be expected for this category.

Mean Number of Tests Per Admission
(Number of Tests/Number of Admissions)
Mean Length of Stay (hours)
DGR
2008
2009
2010
2011
A06B
Tracheostomy w/ ventilation >95hrs + and -
181.10
(10866/60)
646
179.31
(10400/58)
886
159.77
(11823/74)
636
156.77
(12071/77)
696
Z60A
Rehabilitation +
72.86
(7140/98)
1205
74.49
(8045/108)
1070
83.99
(7475/89)
1350
91.16
(10392/114)
1160
L61Z
Haemodialysis
5.26
(8720/1657)
7
4.86
(5413/1113)
7
4.90
(6087/1242)
7
5.27
(5481/1041)
7
E62A
Respiratory
infections +
40.60
(5359/132)
305
36.51
(3395/93)
225
37.94
(3870/102)
244
42.81
(5308/124)
289
F74Z
Chest pain
8.67
(3973/458)
27
9.52
(3978/418)
33
9.08
(4810/530)
29
8.87
(4888/551)
25
A06A
Tracheostomy
w/ ventilation
>95hrs + only
301.05
(6021/20)
2026
296.82
(3265/11)
2437
224.68
(4269/19)
956
250.75
(3009/12)
1150
F62B
Heart failure
& shock –
19.26
(4294/223)
123
21.08
(3141/149)
120
22.23
(4423/199)
134
21.75
(4612/212)
128
E65B
Chronic Obstructive Airways Disease -
16.32
(4602/282)
135
17.88
(3630/203)
132
16.02
(3829/239)
128
17.63
(4319/245)
118
G02A
Major bowel
procedure +
76.11
(2740/36)
471
84.69
(4319/51)
502
71.17
(3274/46)
483
91.88
(5513/60)
445
G67B
Oesophagitis & Gastroenteritis +
9.98
(3382/339)
47
10.11
(3436/340)
44
9.80
(3792/387)
43
9.87
(3059/310)
39
Overall (Top-10 DRGs)
17.28
(57097/3305)
109
19.27
(49022/2544)
126
18.33
(53652/2927)
113
21.36
(58652/2746)
128
DRG code with +: “with catastrophic complications”
DRG code with -: “without catastrophic complications”

Table 11. A comparison, between years, of the mean number of pathology tests ordered in each patient admission, for each of the ten DRG admission codes associated with the highest pathology utilisation.



A more detailed analysis of pathology testing using DRGs comparing test volume, proportions, and rank (in parentheses) of the highest-utilisation pathology tests (all tests accounting for at least the 90th percentile of test volume for each hospital for each year), for patients within the ED who were admitted to a hospital ward with the DRG of F74Z (Chest pain) is presented in Table 12. The highest ranked groups of tests (Troponin, EUC [electrolytes, urea, and creatinine], Automated Differential and Liver Function Tests) were consistently selected and ranked as the four most frequently ordered tests at all the hospitals, for both pre-EMR and post-EMR periods. The mean number of C-Reactive protein tests per ED presentation varied both between hospitals and between years. At three of the EDs the mean number of C-Reactive protein tests per ED presentation was higher in 2011 than in 2008 (Hospital ED “A”: from a mean of 0.02 C-Reactive protein tests per ED presentation, in 2008, to a mean of 0.08 tests per presentation; Hospital ED “D”: from a mean of 0.24 tests to 0.31 tests; and Hospital ED “F”: from a mean of 0.13 tests to 0.21 tests), while the opposite was true for the ED at Hospital ED “E” (from a mean of 0.11 tests to 0.06 tests).
Number of Tests
(Mean Number of Tests per ED Presentation)
% of tests
(rank)
Hospital ED
A
D
E
F
Test
2008
2011
2008
2011
2008
2011
2008
2011
N of Patients
(N of ED presentations)
108
(111)
133
(134)
33
(34)
87
(91)
140
(143)
133
(134)
159
(158)
179
(183)
TROPONIN
133
(1.20)
21.25%
(1)
186
(1.39)
23.72%
(1)
52
(1.53)
22.22% (1)
145
(1.59)
22.52%
(1)
174
(1.22)
19.62%
(1)
177
(1.32)
22.61%
(1)
219
(1.39)
20.20%
(1)
266
(1.45)
21.11%
(1)
EUC
117
(1.05)
18.69% (2)
136
(1.01)
17.35%
(2)
33
(0.97)
14.10%
(2)
91
(1.00)
14.13%
(2)
150
(1.05)
16.91%
(2)
137
(1.02)
17.50%
(2)
165
(1.04)
15.22%
(2)
184
(1.01)
14.60%
(2)
AUTOMATED
DIFF
114
(1.03)
18.21%
(3)
134
(1.00)
17.09%
(3)
33
(0.97)
14.10%
(2)
90
(0.99)
13.98%
(3)
145
(1.01)
16.35%
(3)
133
(0.99)
16.99%
(3)
160
(1.01)
14.76%
(3)
180
(0.98)
14.29%
(3)
LFT
60
(0.54)
9.58%
(4)
71
(0.53)
9.06%
(4)
22
(0.65)
9.40%
(4)
62
(0.68)
9.63%
(4)
126
(0.88)
14.21%
(4)
89
(0.66)
11.37%
(4)
79
(0.50)
7.29%
(5)
117
(0.64)
9.29%
(4)
PT/INR/APTT
19
(0.17)
3.04%
(7)
35
(0.26)
4.46%
(6)
21
(0.62)
8.97%
(5)
50
(0.55)
7.76%
(6)
62
(0.43)
6.99%
(5)
65
(0.49)
8.30%
(5)
99
(0.63)
9.13%
(4)
101
(0.55)
8.02%
(5)
CA MG PHOS
8
(0.07)
1.28%
*(11)
44
(0.33)
5.61%
(5)
16
(0.47)
6.84%
(6)
59
(0.65)
9.16%
(5)
21
(0.15)
2.37%
(9)
50
(0.37)
6.39%
(6)
75
(0.47)
6.92%
(6)
91
(0.50)
7.22%
(7)
GLUCOSE
47
(0.42)
7.51%
(5)
33
(0.25)
4.21%
(7)
14
(0.41)
5.98%
(7)
44
(0.48)
6.83%
(7)
58
(0.41)
6.54%
(6)
12
(0.09)
1.53%
(10)
37
(0.23)
3.41%
(8)
96
(0.52)
7.62%
(6)
Number of Tests
(Mean Number of Tests per ED Presentation)
% of tests
(rank)
Hospital EDADEF
Test20082011200820112008201120082011
D-DIMER LIA
16
(0.14)
2.56%
(9)
22
(0.16)
2.81%
(9)
6
(0.18)
2.56%
*(9)
14
(0.15)
2.17%
(10)
27
(0.19)
3.04%
(7)
14
(0.10)
1.79%
*(9)
38
(0.24)
3.51%
(7)
35
(0.19)
2.78%
*(10)
LIPASE
26
(0.23)
4.15%
(6)
13
(0.10)
1.66%
(11)
6
(0.18)
2.56%
(9)
20
(0.22)
3.11%
*(9)
8
(0.06)
0.90%
(14)
24
(0.18)
3.07%
(7)
34
(0.22)
3.14%
(9)
41
(0.22)
3.25%
(8)
C-REACTIVE
PROTEIN
2
(0.02)
0.32%
(19)
11
(0.08)
1.40%
(12)
8
(0.24)
3.42%
(8)
28
(0.31)
4.35%
(8)
16
(0.11)
1.80%
*(10)
8
(0.06)
1.02%
(11)
20
(0.13)
1.85%
(11)
39
(0.21)
3.10%
(9)
BLOOD GAS
19
(0.17)
3.04%
(7)
31
(0.23)
3.95%
(8)
1
(0.01)
0.16%
(17)
8
(0.06)
0.90%
(14)
20
(0.15)
2.55%
(8)
13
(0.08)
1.20%
(12)
15
(0.08)
1.19%
(12)
TSH
3
(0.03)
0.48%
(16)
3
(0.02)
0.38%
(17)
6
(0.18)
2.56%
(9)
12
(0.13)
1.86%
(11)
5
(0.03)
0.56%
(16)
8
(0.06)
1.02%
(11)
21
(0.13)
1.94%
(10)
17
(0.09)
1.35%
(11)
URINE MICRO
5
(0.05)
0.80%
(14)
17
(0.13)
2.17%
*(10)
3
(0.09)
1.28%
(14)
4
(0.04)
0.62%
(13)
10
(0.07)
1.13%
(13)
5
(0.04)
0.64%
(14)
6
(0.04)
0.55%
(17)
15
(0.08)
1.19%
(12)
AMYLASE
1
(0.01)
0.16%
(25)
2
(0.01)
0.26%
(21)
4
(0.12)
1.71%
(13)
7
(0.08)
1.09%
(12)
25
(0.17)
2.82%
(8)
8
(0.06)
1.02%
(11)
8
(0.05)
0.74%
(15)
4
(0.02)
0.32%
(15)
CK
8
(0.07)
1.28%
(11)
1
(0.01)
0.13%
(25)
5
(0.15)
2.14%
(12)
1
(0.01)
0.16%
(17)
3
(0.02)
0.34%
(17)
1
(0.01)
0.13%
(21)
13
(0.08)
1.20%
(12)
4
(0.02)
0.32%
(15)
PT/INR
11
(0.10)
1.76%
(10)
16
(0.11)
1.80%
(10)
1
(0.01)
0.13%
(21)
CKMB
10
(0.06)
0.92%
*(14)
1
(0.01)
0.08%
(26)
* indicates the lowest ranked test, for each hospital for each year, that must be included for a minimum of the 90th percentile of tests based on test utilisation.

Table 12. A comparison, between 2008 and 2011 at the ED of four hospitals, of the tests (number, rate per presentation, proportion, and rank) ordered for patients within the ED who were eventually admitted to a ward with a DRG of F74Z (Chest pain). (Note: Very low volume tests are not shown.)

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