Models of Neoptolemos et al for Predicting the Risk of Complications Following Therapy for Common Bile Duct Stones

 

Models:

(1) complications after surgery

(2) complications after endoscopic sphincterotomy

(3) complications after either

 

Medical risk factors for surgery:

(1) cardiovascular disease requiring long-term drug therapy

(2) respiratory disease requiring long-term drug therapy

(3) diabetes mellitus treated with oral medication or insulin

(4) any medical condition requiring long-term steroid therapy

(5) major psychiatric disorder (psychosis, dementia)

(6) central nervous system disturbance (hemoplegia, multiple sclerosis, etc.)

 

Parameters for patient undergoing surgery:

(1) medical risk factors

(2) history of previous endoscopic sphincterotomy

(3) total serum bilirubin in µmol/L

Parameter	Finding	Points
medical risk factors	none	0
	1 or more	1
previous endoscopic sphincterotomy	no	0
	yes	1

 

X =

= (0.51 * (points for medical risk factors)) + (0.533 * (points for previous endoscopic sphincterotomy)) + (0.0003 * (serum bilirubin in µmol/L)) - 1.627

 

where:

• The text describes bilirubin as being in mmol/L. However the data in Table 4 shows bilirubin in µmol/L. Using mmol/L and the factors shown would result in very small numbers. Therefore µmol/L will be used instead of mmol/L for serum bilirubin.

 

probability of post-operative complications =

= 1 / (1 + EXP((-1) * X))

 

Parameters for a patient undergoing ERCP with sphincterotomy:

(1) serum albumin in g/L

(2) total serum bilirubin in µmol/L

 

Y =

= (0.004 * (serum bilirubin in µmol/L)) - (0.107 * (serum albumin in g/L)) + 1.46

 

probability of post-operative complications =

= 1 / (1 + EXP((-1) * Y))

 

Parameters for patients irregardless of therapy:

(1) urea in mmol/L

(2) total serum bilirubin in µmol/L

 

Z =

= (0.098 * (urea in mmol/L)) + (0.0032 * (serum bilirubin in µmol/L)) - 2.330

 

probability of post-operative complications =

= 1 / (1 + EXP((-1) * Z))

 

Limitations:

• The models were developed prior to the widespread availability of laparoscopic techniques.