J Endocrinol Metab

Journal of Endocrinology and Metabolism, ISSN 1923-2861 print, 1923-287X online, Open Access

Article copyright, the authors; Journal compilation copyright, J Endocrinol Metab and Elmer Press Inc

Journal website http://www.jofem.org

Original Article

Volume 2, Number 2, April 2012, pages 88-95

Derivation and Validation of a Risk Index to Predict All-Cause Mortality in Type 2 Diabetes Mellitus

Figure 1. Constructing Diabetes Complication Severity Index in Chronic Disease Management System. *ICD-9 CM codes indicate International Classification of Disease, Ninth Revision, Clinical Modification. *Severity index is based on a severity scale for each complication (ICD-9 CM codes) as follows: 0 = normal, 1 = abnormal, 2 = severe abnormal. *Diabetes complication severity score was developed and validated by Yong et al, 2008 [8].

**Table 1.** Characteristics of Type 2 Diabetes Mellitus in National Healthcare Group Polyclinics in 2007
	2 years all-cause mortality, no. (%) of patients
Patient Variable
Age Group, yr
	< 45	3764 (6.3)	1838 (6.2)	1926 (6.4)
	45 - 54	11581 (19.4)	5828 (19.5)	5753 (19.2)
	55 - 64	18124 (30.3)	9053 (30.3)	9071 (30.3)
	65 - 74	16110 (27)	8041 (26.9)	8069 (27)
	75 - 84	8497 (14.2)	4233 (14.2)	4264 (14.3)
	85+	1691 (2.8)	884 (3)	807 (2.7)
Female		32088 (53.7)	16101 (53.9)	15987 (53.5)
Race
	Chinese	42268 (70.7)	21176 (70.8)	21092 (70.6)
	Indian	7854 (13.1)	3882 (13.0)	3972 (13.3)
	Malay	7675 (12.8)	3841 (12.9)	3834 (12.8)
	Others	1970 (3.3)	991 (3.3)	979 (3.3)

Cancer History		1601 (2.7)	827 (2.8)	774 (2.6)
Diabetes Complication Severity Score
	0	33227 (55.6)	16549 (55.4)	16678 (55.8)
	1	12272 (20.5)	6133 (20.5)	6139 (20.5)
	2	7970 (13.3)	4015 (13.4)	3955 (13.2)
	3	3123 (5.2)	1592 (5.3)	1531 (5.1)
	4	1783 (3.0)	909 (3.0)	874 (2.9)
	5+	1392 (2.3)	692 (2.3)	700 (2.3)
Hypertension		47087 (78.8)	23464 (78.5)	23623 (79.1)
Dyslipidiaemia		57071 (95.5)	28542 (95.5)	28529 (95.5)
HbA1c, %
	< 7.1	27115 (45.4)	13589 (45.5)	13526 (45.3)
	7.1 - 8.0	18870 (31.6)	9473 (31.7)	9397 (31.5)
	8.1 - 9.0	6616 (11.1)	3292 (11.0)	3324 (11.1)
	9.1 - 10	2886 (4.8)	1459 (4.9)	1427 (4.8)
	10.1+	3247 (5.4)	1589 (5.3)	1658 (5.5)
	Missing	1033 (1.7)	488 (1.6)	545 (1.8)
LDL-c, mmol/L
	< 2.6	24541 (41.1)	12368 (41.4)	12173 (40.7)
	2.6 - 3.3	17910 (30)	8952 (29.9)	8958 (30)
	3.4 - 4.0	6570 (11)	3304 (11.1)	3266 (10.9)
	4.1+	3386 (5.7)	1683 (5.6)	1703 (5.7)
	Missing	7360 (12.3)	3583 (12.0)	3777 (12.6)
eGFR, mL/min/1.73m²
	Stage 1	13407 (22.4)	6654 (22.3)	6753 (22.6)
	Stage 2	25926 (43.4)	13023 (43.6)	12903 (43.2)
	Stage 3	10642 (17.8)	5394 (18.0)	5248 (17.6)
	Stage 4	1155 (1.9)	581 (1.9)	574 (1.9)
	Stage 5	331(0.6)	159 (0.5)	172 (0.6)
	Missing	8306 (13.9)	4079 (13.6)	4227 (14.1)
HDL-c, mmol/L, mean (SD)		1.26 (0.34)	1.26 (0.34)	1.26 (0.34)
Triglycerides, mmol/L, mean (SD)		1.55 (0.92)	1.55 (0.94)	1.54 (0.89)
Body Mass Index (BMI), kg/m²
	Underweight	21110 (35.3)	10575 (35.4)	10535 (35.3)
	Normal	960 (1.6)	456 (1.5)	504 (1.7)
	Obese I	19867 (33.2)	9967 (33.3)	9900 (33.1)
	Obese II	6660 (11.1)	3343 (11.2)	3317 (11.1)
	Overweight	2126 (3.6)	1035 (3.5)	1091 (3.7)
	Missing	9044 (15.1)	4514 (15.1)	4530 (15.2)
Systolic BP, mm Hg, mean (SD)		132 (14)	132 (14)	132 (14)
Diastolic BP, mm Hg, mean (SD)		77 (8)	77 (8)	78 (8)
Insulin use		5958 (10.0)	2934 (9.8)	3024 (10.1)
Admission Variable
Hospitalization during previous 1 year		6934 (11.6)	3512 (11.7)	3422 (11.5)
Visits to emergency department during previous 1 year		9757 (16.4)	4891 (16.4)	4866 (16.3)
Visits to specialist outpatient consultation		27251 (45.6)	13836 (46.3)	13415 (44.9)

Table 1. Characteristics of Type 2 Diabetes Mellitus in National Healthcare Group Polyclinics in 2007

2 years all-cause mortality, no. (%) of patients

Overall (n = 59,767)

Derivation (n = 29,890)

Validation (n = 29,877)

Patient Variable

Age Group, yr

< 45

3764 (6.3)

1838 (6.2)

1926 (6.4)

45 - 54

11581 (19.4)

5828 (19.5)

5753 (19.2)

55 - 64

18124 (30.3)

9053 (30.3)

9071 (30.3)

65 - 74

16110 (27)

8041 (26.9)

8069 (27)

75 - 84

8497 (14.2)

4233 (14.2)

4264 (14.3)

85+

1691 (2.8)

884 (3)

807 (2.7)

Female

32088 (53.7)

16101 (53.9)

15987 (53.5)

Race

Chinese

42268 (70.7)

21176 (70.8)

21092 (70.6)

Indian

7854 (13.1)

3882 (13.0)

3972 (13.3)

Malay

7675 (12.8)

3841 (12.9)

3834 (12.8)

Others

1970 (3.3)

991 (3.3)

979 (3.3)

Cancer History

1601 (2.7)

827 (2.8)

774 (2.6)

Diabetes Complication Severity Score

33227 (55.6)

16549 (55.4)

16678 (55.8)

12272 (20.5)

6133 (20.5)

6139 (20.5)

7970 (13.3)

4015 (13.4)

3955 (13.2)

3123 (5.2)

1592 (5.3)

1531 (5.1)

1783 (3.0)

909 (3.0)

874 (2.9)

1392 (2.3)

692 (2.3)

700 (2.3)

Hypertension

47087 (78.8)

23464 (78.5)

23623 (79.1)

Dyslipidiaemia

57071 (95.5)

28542 (95.5)

28529 (95.5)

HbA1c, %

< 7.1

27115 (45.4)

13589 (45.5)

13526 (45.3)

7.1 - 8.0

18870 (31.6)

9473 (31.7)

9397 (31.5)

8.1 - 9.0

6616 (11.1)

3292 (11.0)

3324 (11.1)

9.1 - 10

2886 (4.8)

1459 (4.9)

1427 (4.8)

10.1+

3247 (5.4)

1589 (5.3)

1658 (5.5)

Missing

1033 (1.7)

488 (1.6)

545 (1.8)

LDL-c, mmol/L

< 2.6

24541 (41.1)

12368 (41.4)

12173 (40.7)

2.6 - 3.3

17910 (30)

8952 (29.9)

8958 (30)

3.4 - 4.0

6570 (11)

3304 (11.1)

3266 (10.9)

4.1+

3386 (5.7)

1683 (5.6)

1703 (5.7)

Missing

7360 (12.3)

3583 (12.0)

3777 (12.6)

eGFR, mL/min/1.73m²

Stage 1

13407 (22.4)

6654 (22.3)

6753 (22.6)

Stage 2

25926 (43.4)

13023 (43.6)

12903 (43.2)

Stage 3

10642 (17.8)

5394 (18.0)

5248 (17.6)

Stage 4

1155 (1.9)

581 (1.9)

574 (1.9)

Stage 5

331(0.6)

159 (0.5)

172 (0.6)

Missing

8306 (13.9)

4079 (13.6)

4227 (14.1)

HDL-c, mmol/L, mean (SD)

1.26 (0.34)

Triglycerides, mmol/L, mean (SD)

1.55 (0.92)

1.55 (0.94)

1.54 (0.89)

Body Mass Index (BMI), kg/m²

Underweight

21110 (35.3)

10575 (35.4)

10535 (35.3)

Normal

960 (1.6)

456 (1.5)

504 (1.7)

Obese I

19867 (33.2)

9967 (33.3)

9900 (33.1)

Obese II

6660 (11.1)

3343 (11.2)

3317 (11.1)

Overweight

2126 (3.6)

1035 (3.5)

1091 (3.7)

Missing

9044 (15.1)

4514 (15.1)

4530 (15.2)

Systolic BP, mm Hg, mean (SD)

132 (14)

Diastolic BP, mm Hg, mean (SD)

77 (8)

78 (8)

Insulin use

5958 (10.0)

2934 (9.8)

3024 (10.1)

Admission Variable

Hospitalization during previous 1 year

6934 (11.6)

3512 (11.7)

3422 (11.5)

Visits to emergency department during previous 1 year

9757 (16.4)

4891 (16.4)

4866 (16.3)

Visits to specialist outpatient consultation

27251 (45.6)

13836 (46.3)

13415 (44.9)

**Table 2.** Final Logistic Regression Model for Risk of Mortality (Derivation Group Only, n = 29,877)
Variable	Odds ratio (95% CI)
Age	1.07 (1.06 - 1.07)
Cancer history	6.97 (5.81 - 8.36)
Diabetes Complication Severity Score
Category
1	1.95 (1.65 - 2.30)
2	2.69 (2.28 - 3.18)
3	3.93 (3.22 - 4.80)
4	7.13 (5.79 - 8.80)
5+	13.88 (11.28 - 17.09)

Table 2. Final Logistic Regression Model for Risk of Mortality (Derivation Group Only, n = 29,877)

Variable

Odds ratio (95% CI)

Age

1.07 (1.06 - 1.07)

Cancer history

6.97 (5.81 - 8.36)

Diabetes Complication Severity Score

Risk factor	Value	Points
Age ("A")	< 40	0
	40 - 49	1
	50 - 59	3
	60 - 69	5
	70 - 79	6
	80+	8
Cancer history ("C") Diabetes-related Complication (Diabetes Complication Severity Score ) ("C")	Yes	5
	0	0
	1	2
	2	3
	3	4
	4	5
	5+	7

ACC score	Observed probability	Expected probability	Sensitivity	Specificity
0	0.2	0.3	99.9	1.8
1	0.3	0.4	99.4	10.2
2	1.6	0.6	99.3	10.7
3	0.7	0.9	99.3	10.7
4	1.7	1.3	96.2	32.2
5	1.4	1.9	90.2	54.6
6	3.7	2.8	90.2	54.6
7	3.0	4.0	77.3	73.6
8	5.8	5.8	63.7	85.2
9	9.2	8.4	54.4	90.0
10	13.5	11.9	41.6	94.3
11	19.7	16.6	30.0	96.8
12	24.0	22.8	22.8	98.0
13	31.2	30.3	11.8	99.3
14	25.7	39.1	11.8	99.3
15	48.5	48.7	4.1	99.8
16	49.1	58.3	4.1	99.8
17	41.9	67.4	1.4	100.0
18	59.1	75.3	1.4	100.0
20	80.0	86.9	0.0	100.0