Strohaker et al reported the NoCtApp for diagnosis of complicated appendicitis without the need for abdominal CT. The authors are from University of Tuebingen and the Armed Forces Hospital Ulm.
Patient selection: appendicitis
Outcome: recognition of complicated appendicitis (perforation, gangrene, abscess)
Parameters:
(1) age in years
(2) sex
(3) ASA score
(4) duration of symptoms in days
(5) WBC count per microliter
(6) serum CRP in mg/dL
(7) free fluid within the abdomen on ultrasonography
|
Parameter
|
Finding
|
Beta-Coefficient
|
Points
|
|
age
|
<= 40 years
|
0
|
0
|
|
|
41 to 60 years
|
1.374
|
4
|
|
|
> 60 years
|
1.952
|
6
|
|
sex
|
female
|
0
|
0
|
|
|
male
|
0.313
|
1
|
|
ASA score
|
1 or 2
|
0
|
0
|
|
|
3
|
1.070
|
3
|
|
symptom duration
|
<= 2 days
|
0
|
0
|
|
|
> 2 days
|
0.766
|
2
|
|
WBC count
|
<= 14,000 per µL
|
0
|
0
|
|
|
14,001 to 18,000
|
0.684
|
2
|
|
|
> 18,000 per µL
|
1.438
|
4
|
|
serum CRP
|
<= 5 mg/dL
|
0
|
0
|
|
|
5.01 to 10 mg/dL
|
0.992
|
3
|
|
|
> 10 mg/dL
|
2.385
|
7
|
|
free fluid
|
absent
|
0
|
0
|
|
|
present
|
0.625
|
2
|
value of X =
= SUM(beta-coefficients of all the parameters) - 3.151
probability of complicated appendicitis =
= 1 / ( 1 + EXP((-1* (X)))
total point score =
= SUM(points for all of the parameters)
Interpretation:
• minimum point score: 0
• maximum point score: 25
• A score <= 2 has a negative predictive value of 0.96 for complicated appendicitis.
Performance:
• The area under the ROC curve is 0.86.
