Pausawasdi et al reported scores for predicting various measures of success following endobiliary stenting of a malignant biliary obstruction. One equation predicts normalization of total serum bilirubin within 6 weeks of the procedure. The authors are from Siriraj Hospital and Mahidol University in Bangkok.
Patient selection: malignant obstruction of bile duct
Parameters:
(1) extrahepatic biliary obstruction
(2) serum total bilirubin concentration prior to stent placement in mg/dL
(3) material used to make the endobiliary stent
|
Parameter
|
Finding
|
Points
|
|
extrahepatic biliary obstruction
|
no
|
0
|
|
|
yes
|
2
|
|
serum total bilirubin
|
|
-0.3 * (serum TB)
|
|
endobiliary stent
|
metal
|
0
|
|
|
plastic
|
-2
|
total score =
= SUM(points for all of the parameters) + 2
Interpretation:
• minimum score: around -13.6
• maximum score: around 3.6
• The higher the score the greater the chances of success.
• A score >= -2.44 had a sensitivity of 0.6-0.7 and specificity of 0.67-0.74.
• A score >= 1.3 had a high likelihood of bilirubin normalization within 6 weeks.
Performance:
• The area under the ROC curve is 0.78 in the derivation and 0.76 in the validation cohort.
