CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 7, August 2013
AFRICA
277
was above 90, with heterogeneities between the studies (
Q
2
=
8.7,
I
2
=
77%,
p
<
0.1). The pooled OR was 0.61 (95% CI: 0.31–1.21,
p
>
0.05, Fig. 6A) in studies whose sample size was 90 or less, without
heterogeneities between the studies (
Q
2
=
2.39,
I
2
=
16%,
p
>
0.1).
The pooled OR was 0.45 (95%
CI
=
0.27–0.77,
p
<
0.01,
Fig. 6B) in studies whose subjects were European, without
heterogeneities between the studies (
Q
2
=
3.71,
I
2
=
46%,
p
>
0.1). The pooled OR was 0.37 (95%
CI: 0.11–1.27,
p
>
0.05,
Fig. 6B) in studies whose subjects were American and Asian,
with heterogeneities between the studies (
Q
2
=
15.55,
I
2
=
87%,
p
<
0.1).
The pooled OR was 0.28 (95%
CI: 0.19–0.42,
p
<
0.01,
Fig. 6C) in studies whose study method was RCT, without
heterogeneities between the studies (
Q
2
=
2.4,
I
2
=
0%,
p
>
0.1).
The pooled OR was 0.87 (95%
CI: 0.61–1.24,
p
>
0.05, Fig.
6C) in studies whose method of study was non-RCT, without
heterogeneities between the studies (
Q
2
=
0.92,
I
2
=
0%,
p
>
0.1).
By removing one study at a time, a sensitivity analysis was
performed and the model was rerun to determine the effect on
each estimate. It showed that the above meta-analysis estimates
did not change significantly after removal of each study,
implying that these results were statistically reliable.
Discussion
A growing number of studies has shown the efficacy and safety
of SES versus BMS for treating CAD patients with diabetes,
9,29
but the outcome has been controversial. In this analysis, we
retrieved six studies, which included 1 259 CAD subjects with
diabetes, and performed a meta-analysis. It showed that the
SES group had a significant reduction in major adverse cardiac
events, as well as target-lesion revascularisations, compared
with the BMS group. There was no significant difference for
myocardial infarction or mortality.
These results are consistent with a recent study that suggested a
significant reduction in target-vessel revascularisations with SES,
but with similar mortality rates.
9
Unlike this study, in which the
incidence of myocardial infarction was higher, our analysis showed
no difference for myocardial infarctions between the groups.
Another recent study conducted in Europeans confirmed the
efficacy of SES compared with BMS, along with comparable
mortality rates and myocardial infarctions,
11
which further
proved the validity of our analysis. The efficacy and safety of
SES have been receiving more and more supportive reports.
30-33
The uniqueness of our analysis and findings is that it proved the
efficacy and safety of SES in CAD patients with diabetes.
Heterogeneity is one major concern with regard to the validity
of meta-analyses.
26,34
Non-homogeneous data can easily give
misleading results. In our study, the
Q
and
I
2
statistics were
performed to test heterogeneity. For all samples, there was
significant heterogeneity for major adverse cardiac events in the
SES and BMS groups.
We further conducted subgroup analysis according to sample
size, ethnicity and study method. It demonstrated that in the
studies where sample size was
≤
90, method was a RCT and
population was European, the overall major cardiac events
were significantly different between the SES and BMS groups.
Heterogeneity between the studies was decreased after stratifying
the samples. No significant heterogeneity was observed with
RCTs, suggesting an RCT is important for good results. More
high-quality RCTs are therefore warranted.
Another concern for meta-analyses is publication bias, due
to selection of the studies included. In this study, using funnel
plots and Egger’s test,
28,35,36
we found publication bias for
overall major cardiac events, target-lesion revascularisations and
myocardial infarction, but not for overall mortality. Furthermore,
the sensitivity analysis confirmed there was no change if one
study was removed at a time. Although more studies would have
produced better results, overall, our results were statistically
reliable.
Conclusion
This meta-analysis suggested that, compared with BMS, SES
are more effective and safer for reducing major cardiac events in
CAD patients with diabetes. This may indicate the direction for
future trials and clinical implementation.
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Coron Artery Dis
SES
BMS
Weight (%)
Odds ratio
Odds ratio
Study or subgroup
Events
Total
Events
Total
M–H, random, (95% CI)
M–H, random, (95% CI)
Aoki J,
et al.
13
112
8
118
22.2
1.81 (0.72–4.54)
SES
BMS
0.01
0.1 1 10 100
Baumgart D,
et al.
5
94
3
96
12.1
1.29 (0.34–4.97)
Chan C,
et al.
0
54
2
29
10.3
0.10 (0.00–2.18)
Daemen J,
et al.
15
206
16
252
43.0
1.16 (0.56–2.40)
Jimenez-Quevedo P,
et al.
1
80
2
80
6.4
0.49 (0.04–5.56)
Maresta A,
et al.
3
68
2
70
6.1
1.57 (0.25–9.70)
Total (95% CI)
614
645
100.0
1.19 (0.74–1.92)
Total events
37
34
Heterogeneity: Chi
2
= 3.88, df = 5 (
p
= 0.57);
I
2
= 0%
Test for overall effect:
Z
= 0.72 (
p
= 0.47)
Fig. 5. Forest plots of studies with mortality events in the SES group versus the BMS group.
