Risk factors:
(1) severe medical illness
(2) preoperative shock
(3) longstanding perforation
where:
• Severe medical illness included severe cardiac disease, severe pulmonary disease, renal failure, diabetes mellitus, and hepatic precoma.
• Preoperative shock was defined as a preoperative systolic blood pressure < 100 mm Hg.
• Longstanding perforations were defined as those > 24 hours, because definitive surgery was avoided in these perforations.
Factors not associated with increased mortality in the absence of risk factors above:
(1) old age
(2) gross peritoneal soiling
(3) length of ulcer history
|
Parameter
|
Finding
|
Point
|
|
severe medical illness
|
present
|
1
|
|
|
absent
|
0
|
|
preoperative shock
|
present
|
1
|
|
|
absent
|
0
|
|
longstanding perforation
|
> 24 hours
|
1
|
|
|
<= 24 hours
|
0
|
risk score =
= number of risk factors present
= SUM(points for 3 risk factors)
discriminant value =
= (3.40 * (points for medical illness)) + (3.12 * (points for shock)) + (0.68 * (points for delay > 24 hours)) - 0.53
Interpretation:
• minimum risk score: 0
• maximum risk score: 3
• minimum discriminant value: -0.53
• maximum discriminant value: 6.67
Values for the discriminant values showed 3 clusters:
(1) neither severe medical illness nor shock: score -0.53 and 0.13: all survived (low risk)
(2) both severe medical illness and shock: 5.99 and 6.67: all died (high risk)
(3) either severe medical illness or shock: 2.59, 2.87, 3.27, 3.55: variable mortality rate somewhere between 10 and 46% (moderate risk)
