Patient selection: adult (age >= 18 years) with complicated appendicitis (gangrene, rupture)
Exclusions: morbid obesity, autoimmune disease, end-stage renal disease, HIV infection
Outcome: superficial surgical site infection within 30 days after open laparotomy (non-laparoscopic)
Patients received antibiotics prior and after surgery for up to 10 days, initially parenteral then switched to oral.
Parameters:
(1) diabetes mellitus
(2) incision length in cm
(3) operative time in minutes
(4) fecal contamination
|
Parameter
|
Finding
|
Points
|
beta-coefficient
|
|
diabetes
|
absent
|
0
|
0
|
|
|
present
|
1
|
0.96
|
|
incision length
|
<= 7 cm
|
0
|
0
|
|
|
> 7 cm
|
1
|
1.03
|
|
operative time
|
<= 75 minutes
|
0
|
0
|
|
|
> 75 mimutes
|
1
|
1.22
|
|
fecal contamination
|
absent
|
0
|
0
|
|
|
present
|
1
|
1.27
|
number of risk factors =
= SUM(points for all 4 parameters)
X =
= SUM(beta-coefficients) - 3.7
Interpretation:
• minimum number of risk factors: 0
• maximum number of risk factors: 4
• The higher the score the greater the risk of superficial SSI.
|
Number of Risk Factors
|
Risk of Superficial SSI
|
|
0
|
very low
|
|
1
|
low
|
|
2
|
moderate
|
|
3 or 4
|
high
|
probability of SSI =
= 1 / (1+EXP((-1) * X))
Performance:
• The area under the ROC curve is 0.74.
