Pretreatment nomogram to predict the risk of acute urinary retention after I-125 prostate brachytherapy.
OBJECTIVE
Acute urinary retention (AUR) after iodine-125 (I-125) prostate brachytherapy negatively influences long-term quality of life and therefore should be prevented. We aimed to develop a nomogram to preoperatively predict the risk of AUR.


METHODS
Using the preoperative data of 714 consecutive patients who underwent I-125 prostate brachytherapy between 2005 and 2008 at our department, we modeled the probability of AUR. Multivariate logistic regression analysis was used to assess the predictive ability of a set of pretreatment predictors and the additional value of a new risk factor (the extent of prostate protrusion into the bladder). The performance of the final model was assessed with calibration and discrimination measures.


RESULTS
Of the 714 patients, 57 patients (8.0%) developed AUR after implantation. Multivariate analysis showed that the combination of prostate volume, IPSS score, neoadjuvant hormonal treatment and the extent of prostate protrusion contribute to the prediction of AUR. The discriminative value (receiver operator characteristic area, ROC) of the basic model (including prostate volume, International Prostate Symptom Score, and neoadjuvant hormonal treatment) to predict the development of AUR was 0.70. The addition of prostate protrusion significantly increased the discriminative power of the model (ROC 0.82). Calibration of this final model was good. The nomogram showed that among patients with a low sum score (<18 points), the risk of AUR was only 0%-5%. However, in patients with a high sum score (>35 points), the risk of AUR was more than 20%.


CONCLUSIONS
This nomogram is a useful tool for physicians to predict the risk of AUR after I-125 prostate brachytherapy. The nomogram can aid in individualized treatment decision-making and patient counseling.
Roeloffzen
Ellen M
EM
Department of Radiation Oncology, University Medical Center Utrecht, The Netherlands. e.m.a.roeloffzen@umcutrecht.nl
van Vulpen
Marco
M
Battermann
Jan J
JJ
van Roermund
Joep G
JG
Saibishkumar
Elantholi P
EP
Monninkhof
Evelyn M
EM
D000368:Aged; D000726:Androgen Antagonists / Q000008:administration & dosage; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D017024:Chemotherapy, Adjuvant; D003657:Decision Making; D016002:Discriminant Analysis; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D049451:Nomograms; D015588:Observer Variation; D009929:Organ Size; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011788:Quality of Life; D012372:ROC Curve; D012044:Regression Analysis; D018570:Risk Assessment; D001743:Urinary Bladder / Q000473:pathology; D016055:Urinary Retention / Q000209:etiology* / Q000517:prevention & control
D000726:Androgen Antagonists; D007457:Iodine Radioisotopes