Kanao et al developed a model for evaluating a patient with renal stones prior to extracorporeal shock wave lithotripsy (ESWL). This can help to identify patients who may require more careful followup. The authors are from Keio University in Tokyo.
Parameters:
(1) number of stones
(2) length (maximim dimension) in mm
(3) location
Parameter
Finding
Coefficient
number of stones
1
0.96
2 or more
0
length in mm
<= 5
3.02
6 to 10
2.12
11 to 15
1.43
16 to 20
0.52
>= 21
0
location
calix
0
renal pelvis
0.29
proximal ureter
0.89
mid to distal ureter
0.69
X =
= SUM(coefficients for the 3 parameters) - 2.12
probability of being stone-free at 3 months after single extracorporeal shock wave lithotripsy =
= 1 / (1 + EXP((-1) * X))
This model was used to develop the nomogram in Table 3 on page 1455.
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