Nonogram of De Nunzio et al for Predicting Stone Free Status in a Patient with Ureteral Stone Treated with Semi-Rigid Primary Laser Uretero-Lithotripsy
De Nunzio et al reported a nomogram for predicting the likelihood that a patient with a ureteral stone will be stone free after a semi-rigid primary laser uretero-lithotripsy. The authors are from "La Sapienza" University in Rome and Hospital Clinic Barcelona.
Patient selection: ureteral stone treated with semi-rigid primary laser uretero-lithotripsy.
Parameters:
(1) hydronephrosis
(2) length of stone in mm, from 0 to 20
(3) location in ureter
(4) number of stones
points for length =
= 10 - (0.5 * (length))
Parameter
Finding
Points
hydronephrosis
no
4.5
yes
0
location
distal
8.25
other
0
number of stones
1
5
>= 2
0
total score =
= SUM(points for all of the parameters)
Interpretation:
• miinimum score: 0
• maximum score: 27.75
value of X =
= (0.155 * (score)) - 1.417
probability of being stone free =
= 1 / (1 + EXP((-1) * X))
Performance:
• The area under the ROC curve is 0.75.
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