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: 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)
points for IIEF EFD score =
= (2.938 * (score)) - 17.625
points for age =
= 163.64 - (1.182 * (age))
|
Number of Comorbidities
|
Points
|
|
0
|
6.63
|
|
1
|
4.42
|
|
2
|
2.21
|
|
3
|
0
|
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 0
• maximum score: 177.2
value of X =
= 4.534 - (0.04499 * (score))
value of Y =
= (0.04498 * (score)) - 5.902
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 0.76.
