Patient selection: variceal bleeding in a patient with cirrhosis
Outcome: 5-day failure (uncontrolled bleeding, rebleeding, death) from varices
Parameters:
(1) total number of blood units transfused in the first 24 hours
(2) active bleeding
(3) Child-Pugh class
(4) portal vein thrombosis
(5) serum AST in IU/L
|
Parameter
|
Finding
|
Points
|
|
active bleeding
|
no
|
0
|
|
|
yes
|
1
|
|
Child-Pugh class
|
A
|
1
|
|
|
B
|
2
|
|
|
C
|
3
|
|
portal vein thrombosis
|
no
|
0
|
|
|
yes
|
1
|
X for model 1 =
= (0.98 * (points for Child Pugh class)) + (1.12 * (points for portal vein thrombosis)) + (0.003 * (serum AST)) + (0.75 * (points for active bleeding)) - 5.09
probability of failure by model 1 =
= 1 / (1 + EXP((-1) * X))
Y for model 2 =
= (0.82 * (points for Child Pugh class)) + (1.012 * (points for portal vein thrombosis)) + (0.003 * (serum AST)) + (0.30 * (number of units transfused)) - 5.02
probability of failure by model 2 =
= 1 / (1 + EXP((-1) * Y))
Performance:
• The area under the ROC curve is 0.77 for model 1 and 0.79 for model 2.
