Mulhall et al reported nomograms for predicting erectile dysfunction after radical prostatectomy. The authors are from Memorial Sloan Kettering Cancer Center, Cleveland Clinic, and Northwestern University.
Patient selection: status 12-13 months after radical prostatectomy
Outcome: erectile dysfunction at 24 months after surgery, with IIEF EFD >= 24 indicating good outcome and <= 10 as severe erectile dysfunction
Parameters:
(1) baseline International Index of Erectile Function erectile function domain (IIEF EFD) score, from 0 to 30
(2) age of the patient, from 35 to 90 years
(3) comorbidities, from 0 to 3 (> 3 was rare in the population studied)
(4) nerve sparing status, from 2 (perfect on both sides) to 8 (no sparing on both sides)
(5) IIEF EFD score at 12 months
points for IIEF EFD baseline score =
= (1.267 * (score)) - 7.6
points for age =
= 122.727 - (1.364 * (age))
points for IIEF EFD score at 12 months =
= 4.167 - 25
|
Parameter
|
Finding
|
Points
|
|
number of comorbidities
|
0
|
2.28
|
|
|
1
|
1.52
|
|
|
2
|
0.76
|
|
|
3
|
0
|
|
nerve sparing score
|
2
|
22.8
|
|
|
3
|
19.0
|
|
|
4
|
15.2
|
|
|
5
|
11.4
|
|
|
6
|
7.6
|
|
|
7
|
3.8
|
|
|
8
|
0
|
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 0
• maximum score: 228.96
value of X =
= 4.695 - (0.0502 * (score))
value of Y =
= (0.0503 * (score)) - 7.196
probability of IIEF EFD <= 10 at 24 months =
= 1 / (1 + EXP((-1) * X))
probability of IIEF EFD >= 24 at 24 months =
= 1 / (1 + EXP((-1) * Y))
probability of IIEF EFD from 11 to 23 at 24 months =
= 1 - (probability LTE 10) - (probability GTE 24)
Performance:
• The area under the ROC curve was 0.87.
