Kharbanda et al developed 2 decision rules to identify a child with a low risk of appendicitis. A child at low risk can be managed conservatively with careful observation and does not need a CT scan. The authors are from Children's Hospital Boston.
Patient selection: 3 to 18 years of age
Parameters for first rule (derived by logistic regression):
(1) nausea
(2) history of focal right lower quadrant (RLQ) pain
(3) migration of pain
(4) difficulty walking
(5) rebound tenderness and/or pain on percussion
(6) absolute neutrophil count
|
Parameter |
Finding |
Points |
|
nausea |
absent |
0 |
|
|
present |
2 |
|
history of focal RLQ pain |
absent |
0 |
|
|
present |
2 |
|
migration of pain |
absent |
0 |
|
|
present |
1 |
|
difficulty walking |
absent |
0 |
|
|
present |
1 |
|
rebound tenderness or pain on percussion |
absent |
0 |
|
|
present |
2 |
|
absolute neutrophil count |
<= 6,750 per µL |
0 |
|
|
> 6,750 per µL |
6 |
total score for first rule =
= SUM(points for all 6 parameters)
Parameters for second rule (derived by recursive partitioning):
(1) nausea
(2) tenderness maximal in RLQ
(3) absolute neutrophil count
|
Absolute Neutrophil Count |
Nausea |
Maximal Tenderness RLQ |
Percent Appendicitis |
|
> 6,750 per µL |
NA |
NA |
53% |
|
<= 6,750 per µL |
no |
NA |
0% |
|
<= 6,750 per µL |
yes |
no |
0% |
|
<= 6,750 per µL |
yes |
yes |
11% |
|
Absolute Neutrophil Count |
Nausea |
Maximal Tenderness RLQ |
Percent Appendicitis |
|
> 6,750 per µL |
NA |
NA |
44% |
|
<= 6,750 per µL |
no |
NA |
0% |
|
<= 6,750 per µL |
yes |
no |
9% |
|
<= 6,750 per µL |
yes |
yes |
13% |
Interpretation:
• minimum score to the first rule: 0
• maximum score to first rule: 14
• A child was considered low risk by the first rule if the score was <= 5.
Performance:
• The first model has a sensitivity of 99% in the derivation set and 96% in the validation set. The specificity was not stated but is 30% in the ROC curve in Figure 2. The NPV was 96% and negative likelihood ratio 0.102.
• The second model has a sensitivity of 100% in the derivation set and 98% in the validation set. The NPV was 97.5% and negative likelihood ratio 0.058.
Specialty: Gastroenterology, Pedatrics, Surgery, general
