Patient selection: open repair of an infrarenal AAA
Complications: respiratory, cardiac, renal, gastrointestinal, neurological, hepatic, vascular, 30-day mortality
Risk factors:
(1) age > 65 years
(2) aortic occlusion time > 90 minutes
(3) COPD with FEV1 (<= 70% of predicted)
(4) emergency surgery
(5) history of cardiac dysfunction
|
Risk Factor
|
Hazard Ratio
|
Percent with Complication
|
|
age > 65 years
|
1.6
|
10%
|
|
occlusion time > 90 minutes
|
2.4
|
20%
|
|
COPD
|
4.4
|
30%
|
|
emergency surgery
|
6.1
|
33%
|
|
cardiac dysfunction
|
2.1
|
20%
|
If more than 1 risk factor was present, then overall percent with complications was approximated by:
overall risk of complication =
= SUM(percentages for risk factors) – (adjustment factor)
|
Number of Risk Factors
|
Adjustment Factor
|
|
2
|
0%
|
|
3
|
10%
|
|
4
|
20%
|
|
5
|
30%
|
Alternatively a logistic regression model can be calculated:
X =
= (0.3 if age > 65) + (1.3 if emergency) + (1.1 if COPD) + (0.6 if cardiac dysfunction) + (1.1 if COPD) + (0.7 if aortic occlusion time > 90 minutes) – 2
probability of complication =
= 1 / (1 + EXP((-1) * X))
