Newman et al developed a risk index for predicting the chances of stroke in patients undergoing coronary artery bypass graft (CABG) surgery. This can be used preoperatively to identify patients who may require more aggressive or alternative management. The study was performed by members of the McSPI Research Group (Multicenter Stroke Prevention) representing 24 academic medical centers in the United States.
Parameters (defined on page II-75):
(1) age over range of 25 to 95 years
(2) unstable angina
(3) diabetes mellitus (type I or II; insulin use)
(4) history of symptomatic neurologic disease (previous stroke or TIA)
(5) prior CABG
(6) history of vascular disease (claudication, atherosclerotic vascular disease or previous vascular surgery)
(7) history of pulmonary disease (emphysema, chronic bronchitis, asthma, restrictive lung disease)
NOTE: These risk factors are not modifiable prior to surgery, although interventions can be taken (antiplatelet agents, etc.) that can reduce risk associated with the factors.
points for age between 25 and 95 =
= (1.4347 * (age in years)) – 36.122
where:
• The linear equation is based on data from Figure 1 (page II-78) being processed in JMP.
• If age is < 25 years, 0 points is assigned. If over 95, 100 points.
|
Parameter
|
Finding
|
Points
|
|
unstable angina
|
present
|
14
|
|
|
absent
|
0
|
|
diabetes
|
present
|
17
|
|
|
absent
|
0
|
|
history of neurologic disease
|
present
|
18
|
|
|
absent
|
0
|
|
prior CABG
|
present
|
15
|
|
|
absent
|
0
|
|
history of vascular disease
|
present
|
18
|
|
|
absent
|
0
|
|
history of pulmonary disease
|
present
|
15
|
|
|
absent
|
0
|
from Figure 1, page II-78 and text page II-77
total points =
= SUM(points for all 7 parameters)
Interpretation:
• minimum score: 0
• maximum score: 198
|
Total Score
|
Probability
|
|
< 62
|
< 1%
|
|
62 to 100
|
see first equation below
|
|
100 to 150
|
see second equation below
|
|
> 150
|
> 30%
|
from Figure 1, page II-78
risk in percent over range of 62 to 100 points =
= (0.0000194 * ((points)^2)) - (0.002096 * (points)) + 0.06525
risk in percent over range of 100 to 150 points =
= (0.0000739 * ((points)^2)) - (0.01328 * (points)) + 0.6393
