Vol.1, No.3, 139-145 (2009)
doi:10.4236/health.2009.13023
SciRes Copyright © 2009 Openly accessible at http://www.scirp.org/journal/HEALTH/
Health
Long-term survival and prognostic implications of
Chinese type 2 diabetic patients with coronary artery
disease after coronary artery bypass grafting
Ming C Hsiung1, Tao-Hsin Tung2, Chung-Yi Chang3, Yi-Cheng Chuang3, Kuo-Chen Lee3,
Sung-How Sue3, Yi-Pen Chou4, Richard Hsiung1, Chien-Ming Huang1, Chang-Chyi Lin1,
Wei-Hsian Yin1, Mason S Young1, Jeng Wei3*
1Division of Cardiology, Department of Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan
2Department of Medicine Research and Education, Cheng-Hsin General Hospital, Taipei, Taiwan
3Division of Cardiovascular Surgery, Cheng-Hsin General Hospital, Taipei, Taiwan;
4Department of Anesthesiology, Cheng-Hsin General Hospital, Taipei, Taiwan
*Corresponding author
Received 13 August 2009; revised 11 September 2009; accepted 14 September 2009.
ABSTRACT
This study was conducted to determine the sur-
vival rates of type 2 diabetic patients after coro-
nary artery bypass grafting (CABG) surgery, and
the prognostic factors related to all-cause mor-
tality during a 7-year follow-up. The medical re-
cords of 816 type 2 diabetic patients who un-
derwent primary, isolated CABG surgery during
1997-2003 were studied. The Kaplan-Meier me-
thod and Cox regression were used to estimate
survival and the independence of prognostic
factors associated with all-cause mortality. One
hundred and five out of 816 patients expired
during the 7-year period. The overall survival
rate was 83.5% (95%CI: 78.7-88.3%). Associated
prog- nostic factors varied by gender. For males,
but not for females, smoking (RR=3.44, 95%CI:
1.01- 11.70), myocardial infarction (RR=4.77,
95% CI: 1.23-18.86), respiratory failure (RR=4.21,
95% CI: 1.48-7.99), cardiogenic shock (RR=12.58,
95% CI: 3.25-20.77), and congestive heart failure
(RR= 3.77, 95%CI: 1.10-13.45) were significantly
related to all-cause mortality. Older age at sur-
gery (RR= 1.15, 95%CI: 1.04-1.27), emergent op-
eration (RR= 21.29, 95%CI: 10.03-39.43), pul-
monary ede-ma (RR=7.72, 95%CI: 1.89-15.59),
and days of ICU stay (RR=1.05, 95%CI: 1.02-1.09)
were significant- ly related to all-cause mortality
in females only. In conclusion, several gen-
der-related differences were noted pertaining to
all-cause mortality and its relationship to smok-
ing, myocardial infarction, respiratory failure,
cardiogenic shock, congestive heart failure,
older age at surgery, emergent operation, pul-
monary edema, and days of ICU stay.
Keywords: Coronary Artery Bypass Grafting;
Gender Difference; Prognostic Factors; Survival;
Type 2 Diabetes
1. INTRODUCTION
Diabetes mellitus is viewed as a major risk factor for car-
diovascular disease, and coronary heart disease is the
leading cause of death in adult diabetics [1]. In general,
around 20% of patients undergoing coronary artery bypass
surgery (CABG) suffer from diabetes mellitus [1]. In ad-
dition, diabetics have a higher mortality than patients
without diabetes after CABG surgery [2,3]. Choosing this
type of surgical therapy for patients depends on the esti-
mate of the risk of the procedure and the possible benefits
compared with alternative forms of therapy. Long-term
outcome among diabetics with coronary artery disease
(CAD) after CABG is associated with severity of diabetes
at the time of surgery [4]. This observation suggests that
early detection of this disorder followed by early treatment
could improve both survival and quality of life.
In Taiwan, the remarkable economic achievements of
the last 40 years have resulted in a great improvement in
living standards and in an increase in life expectancy.
Type 2 diabetes in adults is one of the global public health
problems in the Taiwanese population. Screening for type
2 diabetes by the natural history of diabetes, fasting
plasma glucose (FPG), and oral glucose tolerance test
(OGTT) showed the overall prevalence of type 2 diabetes
in Taiwan to be 5-9% and 11-13% for residents above 20
or 40 years of age, respectively [5-11]. From the view-
point of evidence-based medicine, it is not only important
to be cognizant of the long-term survival of diabetic pa-
tients after CABG, but also to explore the complete
spectrum of demographic and biological markers that

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140
may be related to survival rate. To the best of our know-
ledge, the long-term survival of Chinese type 2 diabetic
patients with CAD undergoing CABG surgery has not
been carefully examined. Some uncertainty still exists
regarding the influence of gender on long-term survival
and on associated risk factors for long-term survival for
these patients after CABG surgery. Thus, in order to de-
termine the long-term survival of and associated risk
factors for diabetic patients after CABG surgery, a long-
term survival study was performed.
Because long-term prognosis after CABG surgery in
relation to gender has not been closely evaluated among
type 2 diabetic patients in Taiwan, the present study was
designed to explore the possibility of gender-related dif-
ferences in risk factors, because such differences might
have important implications for understanding the value
of individual prognostic factors for estimation of long-
term survival of diabetic patients after surgery. The pur-
pose of this study was to determine the long-term (7-year
follow-up) survival rate of each gender after primary,
isolated CABG surgery, and to identify the associated
prognostic factors related to all-cause mortality among
Chinese type 2 diabetic patients.
2. MATERIALS AND METHODS
2.1. Patient Population
Between January 1997 and December 2003, a total of 898
type 2 diabetic patients with CAD underwent CABG
surgery at the Division of Cardiovascular Surgery and
Heart Center, Cheng-Hsin General Hospital, a fully cer-
tified regional and teaching hospital with 757 beds in
Taipei, Taiwan. Of the 898 type 2 diabetic patients, 66
(7.3%) were excluded due to simultaneous valve surgery
and another 16 (1.8%) patients were excluded due to
repeated CABG surgery. The remaining 816 patients who
underwent primary, isolated CABG surgery because of
CAD without concomitant valve procedures and without
previous history of CABG participated in the evaluation.
Seventy-one per cent (581/816) of these participants were
males.
2.2. Data Collection
Patients’ demographic characteristics and surgical vari-
ables were retrieved from medical records and computer
files. The hospital records of each diabetic patient were
reviewed by well trained, senior chart reviewers using a
standard data collection form. Demographic information,
presence of pre-existing co-morbidities and associated
medications at admission and discharge were obtained
from the nursing and medical histories. Indicators of
postoperative recovery and complications were identified
from the details of patient’s progress notes. Subjects were
divided into three categories according to smoking or
alcohol drinking: current users, ex-users, and non users.
We combined current users and ex-users as the user group.
The identification of type 2 diabetes was based on the
WHO definition in 1999 [12]: subjects with FPG126
mg/dl or 2 h post-load 200mg/dl were defined as indi-
viduals with type 2 diabetes. Hypertension was defined as
systolic blood pressure 140 mmHg or diastolic blood
pressure 90 mmHg [13]. Hyperlipidaemia was defined
as one or more of the following: total cholesterol 200
mg/dl; triglyceride 200 mg/dl; HDL < 35 mg/dl [14].
Subjects featuring a personal disease history of type 2
diabetes, hypertension, or hyperlipidaemia and who had
received medication to treat such conditions were viewed
as “known cases” of such disease. In addition, for diabetic
patients after CABG who died in the hospital, case re-
cords such as autopsy findings were used for information
about the causes of death. For those patients who died
outside the hospital, information including autopsy find-
ings, scheduled investigations, and death certificates were
collected. In addition, access to hospital records was
approved by the hospital human subjects review board at
Cheng-Hsin General Hospital.
2.3. Operative Technique
The operative procedures for CABG surgery have been
described in previous studies [15-17]. The CABG opera-
tions were performed by means of a median sternotomy
with the aid of extracorporeal cardiopulmonary bypass
hemodilution (hematocrit, 25% to 30%) and moderate
hypothermia (25 to 28C). Cardiopulmonary bypass used
an ascending aortic cannula followed by a two-stage
venous cannula. Myocardial preservation was achieved
with a hypercalcemic, hypothermic crystalloid solution
and external cooling with ice slush or a cold saline solu-
tion. Crystalloid cardioplegia was infused through the
aortic root at least every 20 minutes and was infused into
each completed vein graft in addition to the aortic root
infusion. Blood cardioplegia was usually used for patients
with left ventricular hypertrophy, cardiogenic shock, or
acutely occluded coronary arteries. Venting was per-
formed primarily via the aorta, and if necessary, via the
pulmonary artery. The myocardial temperature was
monitored and kept below 15C. After completion of all
distal anastomoses, the patient was warmed systemically
to 37C, while warm cardioplegic solution followed by
warm blood was given by the antegrade method.
2.4. Statistical Analysis
Statistical analysis was performed using SAS software.
Prognostic predictors and all-cause mortality were de-
termined by univariate and multivariate techniques. In the
univariate analysis, chi-square testing or two-sample

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Table 1. Comparison of baseline characteristics among type 2 diabetic patients with CAD after CABG surgery (n=816).
Male
(n=581)
Female
(n=235)
Total
(n=816)
n (%) n (%) n (%)
p-value for t-test or
2-test
Categorical variables
Known case of diabetes 385 (66.3) 165 (70.2) 550 (67.4) 0.28
Emergent operation 2 (0.3) 3 (1.3) 5 (0.6) 0.12
Smoking 160 (27.5) 27 (11.5) 187 (22.9) <0.0001
Alcohol drinking 82 (14.1) 16 (6.8) 98 (12.0) 0.005
MI (Inferior or Posterior) 227 (39.1) 77 (32.7) 304 (37.3) 0.09
Hypertension 417 (71.8) 185 (78.7) 602 (73.8) 0.04
Hyperlipidemia 227 (39.1) 90 (38.3) 317 (38.9) 0.84
COPD 36 (6.2) 14 (6.0) 50 (6.1) 0.90
PAOD 24 (4.1) 16 (6.8) 40 (4.9) 0.11
Pulmonary edema 53 (9.1) 32 (13.6) 85 (10.4) 0.06
Old CVA 74 (12.7) 32 (13.6) 106 (13.0) 0.73
Renal failure 82 (14.1) 49 (20.9) 131 (16.1) 0.02
Sepsis 8 (1.4) 6 (2.6) 14 (1.7) 0.24
UGI bleeding 9 (1.6) 4 (1.7) 13 (1.6) 0.87
Respiratory failure 26 (4.5) 10 (4.3) 36 (4.5) 0.93
Cardiogenic shock 39 (6.7) 11 (4.7) 50 (6.1) 0.30
Unstable angina 194 (33.4) 92 (39.1) 286 (35.0) 0.08
Pre PTCA 102 (17.6) 31 (13.2) 133 (16.3) 0.16
CHF 62 (10.7) 25 (10.6) 87 (10.7) 0.94
Type of bypass (arterial/venous) 464/117 (79.9
/20.1) 162/73 (68.9 /31.1) 626/190 (76.7 /23.3) 0.001
Continuous variables
Duration of diabetes 12.644.85 14.785.32 13.574.97 0.01
Operation age (yrs) 64.0210.05 66.508.18 64.749.61 0.0003
FPG (mg/dl) 169.1107.6 201.2106.6 178.498.2 0.002
HbA1c (%) 8.22.0 8.41.9 8.22.0 0.54
SBP(mmHg) 135.020.7 141.122.2 136.921.4 0.02
DBP(mmHg) 76.711.9 77.313.8 75.912.6 0.11
BMI (Kg/m2) 26.717.8 24.94.2 26.115.0 0.15
Cholesterol (mg/dl) 189.344.3 204.3131.8 193.950.0 0.002
Triglyceride (mg/dl) 190.2147.0 204.960.4 194.3142.8 0.32
BUN (mg/dl) 23.417.6 24.415.0 23.716.8 0.56
Creatinine (mg/dl) 1.701.92 1.610.68 1.670.85 0.63
Uric acid (mg/dl) 7.55.6 7.56.5 7.55.9 0.91
AST (U/L) 50.057.0 42.541.5 47.864.8 0.37
ALT (U/L) 40.6107.0 38.625.5 37.291.6 0.19
HDL(mg/dl) 38.511.7 49.967.5 41.636.7 0.09
LDL (mg/dl) 125.438.0 131.848.1 127.141.0 0.18
RBC (103/ul) 4.33.0 4.03.7 4.33.2 0.28
WBC (103/ul) 9.44.5 15.975.4 11.340.6 0.10
Hs-CRP(mg/dl) 0.1890.177 0.1790.164 0.1850.152 0.51
Ischaemic time (min) 61.6441.01 65.1538.65 62.6540.35 0.26
Cardiopulmonary bypass time (min) 104.9968.65 111.9167.68 106.9868.40 0.19
CAD number 2.830.44 2.740.54 2.800.47 0.02
CABG number 3.130.97 3.011.02 3.100.99 0.12
Pre-operation LVEF (%) 50.9319.68 54.0919.91 51.8419.78 0.03
Post-operation LVEF (%) 55.2517.24 57.7218.58 56.0117.68 0.17
ICU stay (days) 6.447.17 8.6413.88 7.089.64 0.02
CAD: coronary artery disease, CABG: coronary artery bypass grafting, MI: myocardial infarction, COPD: chronic obstructive pulmonary disease,
PAOD: peripheral arterial occlusive disease, CVA: cerebrovascular accident, PTCA: percutaneous transluminal coronary angioplasty, CHF: congestive
heart failure.

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Table 2. Multivariate analysis using Cox regression model of risk factors associated with the all-cause mortality that all univariate-
significant factors were included among type 2 diabetic patients with CAD after CABG surgery.
All causes of death (yes vs no)
Male Female Total
Va ri abl e RR (95%CI) RR (95%CI) RR (95%CI)
Gender (male vs female) ----- ----- ----- ----- 0.26 (0.13-0.54)
Operation age (yrs) 1.03 (0.97-1.10) 1.15 (1.04-1.27) 1.05 (1.00-1.10)
Emergent operation (yes vs no) 10.56 (0.67-20.06) 21.29 (10.03-39.43) 12.45 (0.21-22.77)
Smoking (yes vs no) 3.44 (1.01-11.70) 2.56 (0.35-18.48) 2.03 (0.82-5.00)
Myocardial infraction (yes vs no) 4.77 (1.23-18.86) 1.46 (0.13-2.83) 3.31 (1.27-6.80)
Pulmonary edema (yes vs no) 1.55 (0.53-2.39) 6.56 (1.22-15.21) 2.00 (0.33-3.51)
Sepsis (yes vs no) 6.50 (0.61-12.41) 4.97 (0.19-19.81) 5.67 (0.42-13.27)
Respiratory failure (yes vs no) 4.21 (1.48-7.99) 3.10 (0.01-5.03) 3.65 (1.12-10.88)
Cardiogenic shock (yes vs no) 12.58 (3.25-20.77) 1.40 (0.16-12.61) 6.53 (2.00-19.64)
Congestive heart failure (yes vs no) 3.77 (1.10-13.45) 2.91 (0.82-10.24) 3.76 (1.37-8.92)
HbA1c (%) 1.28 (1.01-2.68) 2.87 (1.56-4.72) 1.81 (1.03-3.00)
Type of bypass (arterial vs venous) 0.39 (0.22-0.53) 0.67 (0.47-0.81) 0.57 (0.30-0.74)
Ischaemic time (min) 1.00 (0.97-1.03) 1.01 (0.94-1.08) 1.00 (0.97-1.03)
Cardiopulmonary bypass time (min) 1.01 (0.98-1.02) 0.99 (0.96-1.04) 1.00 (0.98-1.02)
Pre-operation LVEF (%) 0.96 (0.93-1.00) 0.94 (0.89-1.00) 0.96 (0.93-0.98)
Post-operation LVEF (%) 0.98 (0.93-1.04) 0.98 (0.93-1.03) 1.00 (0.97-1.05)
ICU stay (days) 1.01 (0.98-1.05) 1.05 (1.02-1.09) 1.04 (1.02-1.06)
CAD: coronary artery disease, CABG: coronary artery bypass grafting, LVEF: left ventricular ejection fraction
independent Student’s t-testing was applied for discrete or
continuous variables, respectively. The Kaplan-Meier
method was used to estimate the cumulative survival of
diabetic patients after CABG surgery. Multiple Cox re-
gression was used to investigate the independence of
factors associated with all-cause mortality after CABG
surgery when variables were significant by univariate
analysis. Subjects were considered as censored cases if
the outcomes were not available. A p-value of < 0.05 was
considered statistically significant. The results are pre-
sented as means  standard deviations (SDs).
3. RESULTS
3.1. Baseline Characteristics
Table 1 shows the comparison of baseline characteristics
between males and females among diabetic patients with
CAD after CABG surgery. The females differed from the
males in the following ways. Females had a lower pro-
portion of smoking (11.5% vs 27.5%), alcohol con-
sumption (6.8% vs. 14.1%), arterial bypass received
(68.9% vs 79.9%) and a lower CAD number (2.740.54
vs 2.830.44) than males. Females had a higher pro-
portion of hypertension (78.7% vs 71.8%) and renal
failure (20.9% vs 14.1%), were older (66.508.18 yr vs
64.0210.05 yr), had a longer duration of diabetes
(14.785.32 yr vs 12.644.85 yr), had higher FPG
(201.2106.6 mg/dl vs 169.1107.6 mg/dl), SBP
(141.122.2 mmHg vs 135.020.7 mmHg) and cho-
lesterol (204.3131.8 mg/dl vs 189.344.3mg/dl), had
longer days of ICU stays (8.6413.88 yr vs 6.447.17),
and had better preoperative LVEF (54.0919.91% vs
50.9319.68%).
3.2. Survival Rates, Deaths, and Causes of
Death
One hundred and five out of 816 study patients died
during the 7-year follow-up. Of these deaths. The major
causes of death were septic shock (35.2%) and heart
failure (29.5%). As Figure 1 shows, the 1-month, 1-year,
3-year, 5-year, and 7-year cumulative survival among
diabetic patients with CAD after CABG surgery were
95.96% (95% confidence interval (CI): 94.61-97.31%),
92.83% (95%CI: 91.04-94.62%), 88.80% (95%CI: 86.51-
91.09%), 85.56% (95%CI: 83.33-87.79%), and 83.51%
(95%CI: 80.12-86.90%), respectively. A statis- tical sig-
nificance (p=0.04) of gender difference was found for
seven-year cumulative survival after CABG surgery
(males: 86.01% vs females: 77.65%).
3.3. Risk Factors for Mortality
The effect of independently associated risk factors upon
all-cause mortality among diabetic patients with CAD
after CABG was examined using the multiple Cox re-
gression models. As is depicted in Table 2, subsequent to

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0
10
20
30
40
50
60
70
80
90
100
01234567
year
survival (%)
Total (105/816)
Male(68/581)
Female(37/235)
Figure 1. Seven-year cumulative survival among type 2 dia-
betic patients with CAD after CABG surgery in males versus
females.
adjustment for confounding factors, gender (male vs.
female, RR=0.26, 95%CI: 0.13-0.54), age at surgery
(RR=1.05, 95%CI: 1.00-1.10), respiratory failure (yes vs.
no, RR=3.65, 95%CI: 1.12-10.88), cardiogenic shock
(yes vs. no, RR=6.53, 95%CI: 2.00-19.64), congestive
heart failure (yes vs. no, RR=3.76, 95%CI: 1.37-8.92),
HbA1c (RR=1.81, 95%CI: 1.03-3.00), type of bypass
(arterial vs venous, RR=0.57, 95%CI: 0.30-0.74), preop-
erative LVEF (RR=0.96, 95%CI: 0.93-0.98), and days of
ICU stay (RR=1.04, 95%CI: 1.02-1.06) appeared to be
statistically significantly related to all-cause mortality.
The dramatically different results of multiple Cox re-
gression analyses of the data stratified by gender also
show in Table 2.
4. DISCUSSION
4.1. Implications of Gender Difference as
Regards Associated Risk Factors for
All-Cause Mortality
Diabetes is known as a determinant of prognosis in CAD
and may pose an increased risk for major complications
during CABG surgery [3,18]. Diabetic patients represent
about 20% of patients undergoing CABG surgery [19].
Although previous studies have shown that diabetic pa-
tients with CAD have worse long-term survival after
CABG than non-diabetics [1,2], the plausible biological
mechanisms that could link diabetes to the early and late
outcome of CABG remain uncertain. The extent of vas-
cular compromise in diabetes is of particular relevance in
CAD patients, as it might account for the more severe
coronary artery pathology and might also impair the
biological integrity of the bypass grafts [3,20,21]. Pre-
served functional and structural properties of CABG
conduits are essential for a successful myocardial revas-
cularization [3,21].
The continuing surgical and technical improvements in
the operative management of CAD patients who undergo
CABG surgery, as well as consistently better anesthetic
and postoperative care, might have made it difficult to
identify any specific gender-related risk factors associ-
ated with all-cause mortality. However, our results
showed that diabetic females with CAD who were re-
ferred for CABG surgery clearly differed from males in
that they were older and had a higher proportion of hy-
pertension and renal failure. This finding not only implies
that females were at a later disease stage or had more
serious symptoms than males before being referred for
CABG surgery, but also that associated chronic diseases
were major risk indicators for females with CAD [17,22].
In addition, females more frequently had renal dysfunc-
tion. To some extent, this might be explained by older age
and more frequent histories of personal disease such as
diabetes mellitus and hypertension [22].
In the present study, female diabetic patients with CAD
had slightly elevated all-cause mortality during the 7-year
study when compared to male patients. Our findings are
in agreement with previous experiences focused on all
CAD population that showed gender differences in late
mortality [17,22]. They are also in agreement with a large
study taking major risk factors into account that showed
that there were no substantial differences in the long-term
survival of males and females after CABG surgery [22].
Although there seem to be only small differences overall
in long-term survival after CABG surgery between males
and females, there may be greater gender differences in
specific patient subgroups. But after adjustment for con-
founding factors, female sex was still independently as-
sociated with all-cause mortality in the current study. This
difference between male and female may become of
greater importance than in earlier times because the
population of patients undergoing CABG surgery has
aged, there are more patients with abnormal pre- and
postoperative LVEF and the patient populations have
more diffuse diseases [16,22].
It should be noted that a difference in survival rates in
females and males occurs after CABG surgery about 4 to
5 years in this study. Previous studies have also shown
that after adjustment for all independent predictors of
long-term mortality, female sex was an independent pre-
dictor of improved 5-year survival [23]. While the in-
formation yielded by univariate analyses was valuable,
the relationships between predictors and all-cause mor-
tality among diabetic patients with CAD after CABG
surgery were far too complex to be answered completely
by univariate analysis. It has been well documented in
many academic studies that females presenting for CABG
have a vastly different preoperative risk profile than that
of their male counterparts [23]. The risk profiles of males
and female are quite different and indicate that although it
is usually appropriate to directly compare the two groups,
male and female, with respect to a specific predictor, the
predictor might be inappropriate. The use of multivariate
models is particularly important because they fully ac-
p-value for
log-rank test=0.04

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144
count for all related important risk factors. In this study,
some risk factors for all-cause mortality were detrimental
to males and others were more detrimental to females
after CABG surgery. Greater adverse preoperative char-
acteristics such as diabetic females being older and hav-
ing more associated diseases can be suggested as one
explanation of the higher mortality rates among female.
Since female gender was an independent predictor of
all-cause mortality in the multivariate analysis, discrep-
ancies in preoperative demographic or clinical charac-
teristics could only explain part of the increased mortality
rates among diabetic females after CABG surgery.
However, dissimilarities in profiles between female and
male diabetic patients might contribute to the debate
about the gender difference in outcome after CABG sur-
gery [23,24]. In addition, increased mortality among
female patients was probably due to the fact that females
had more comorbid conditions than did men at the time of
referral, perhaps because they were not being evaluated
aggressively enough [25]. From the viewpoint of pre-
ventive medicine, although discrepancies suggest that
associated predictive variables for long-term survival
after CABG surgery differ between hospitals and could
change with time, regular identification of risk factors
makes it possible to focus attention on current problems
to minimize surgical risk and reduce mortality, especially
among females. Clinical decision making and follow-up
should also not be influenced by stereotypes but by spe-
cific findings.
4.2. Methodological Considerations
Although based on the follow-up study design, that is,
being prospective in design as well as including all dia-
betic patients with CAD who underwent CABG surgery
in a well defined patient population for 7 years, we not
only determined the hospital mortality, but also further
explored the cumulative survival and prognostic factors
related to all-cause mortality among diabetic patients with
CAD after CABG surgery. The present study still has
some limitations that need to be considered while as-
sessing the results. First, some of the clinical variables
obtained from medical records could have resulted in
misclassification bias. Nevertheless, it seems reasonable
to assume that if misclassification bias was present, it was
not related to gender and all-cause mortality, thus could
be viewed as nondifferential misclassification. Second,
potential Berkson’s bias (selection bias) was inevitable
due to the hospital-based study design. This population
was not only not exactly representative of the whole
general population, but it was also difficult to estimate the
survival of a matched total population sample in Taiwan,
preferably in the region of Taipei. Third, due to having no
information on the quantity and duration of some risk
factors such as smoking and alcohol drinking, we could
not clarify the dose-response effect between specific
personal habits and all-cause mortality. Fourth, the female
sample size might not be large enough to identify the
exact confidence interval of related prognostic factors.
Further studies should be conducted with larger sample
sizes for female to re-examine gender-specific prognostic
factors for long-term survival among diabetic patients
with CAD after CABG surgery.
5. CONCLUSIONS
The all-cause mortality of diabetic patients with CAD
after CABG surgery and several gender-related differ-
ences pertaining to all-cause mortality were investigated,
including the relationships between all-cause mortality
and smoking, myocardial infarction, cardiogenic shock,
respiratory failure, congestive heart failure, older age at
surgery, emergent operation, pulmonary edema, and days
of ICU stay. In order to increase long-term survival
among diabetic patients with CAD, adequate diagnosis
and treatment risk factors after CABG surgery are essen-
tial.
6. ACKNOWLEDGEMENTS
This study was presented partly in the 2nd International Congress on
“PREDIABETES and the METABOLIC SYNDROME”, Barcelona,
Spain, 2007.
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