title: Development, validation and comparison of two nomograms predicting prostate cancer at initial 12-core biopsy.
abstract: OBJECTIVE
  Our aim was to establish, validate and compare two nomograms in an Iranian population for the first time using clinical, laboratory and transrectal ultrasonography (TRUS) findings for predicting prostate cancer at initial biopsy.
  
  
  METHODS
  Data were collected on a total of 916 men referred for an initial prostate biopsy in our center in a 7-year period. Variables analyzed included age, prostate-specific antigen (PSA), free/total PSA (%fPSA), digital rectal examination (DRE) findings, prostate volume (PV) and presence of hypoechoic lesion on TRUS. Univariate logistic regression models were fitted to test cancer predictors. Two multivariate logistic regression models were fitted to create nomograms. Both models were internally validated. Calibration of nomograms was assessed graphically. The area under the receiver operating characteristic curve (AUC) was calculated as a scale of discrimination and predictive accuracy and also used to compare models.
  
  
  RESULTS
  Prostate cancer was detected in 221/669 (33%) men. Based on univariate logistic regression, all of variables except DRE were significant predictors of prostate cancer, with highest AUC for PV (AUC 0.696, 95% CI 0.653-0.738).AUC of nomogram with and without TRUS findings and PSA alone were 0.791, 0.721 and 0.624, respectively. In internal validation, both nomograms had acceptable calibration plots.
  
  
  CONCLUSIONS
  Our nomogram based on age, DRE, PSA, %fPSA and TRUS finding was significantly more accurate in predicting initial prostate biopsy outcome in men.
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Nowroozi
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.
authors.forename: Shahab
authors.initials: S
authors.lastname: Amini
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.|Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Amir
authors.initials: A
authors.lastname: Kasaeian
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.
authors.forename: Mansour Jamali
authors.initials: MJ
authors.lastname: Zavarehei
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.|Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Eshraghian
authors.affiliation: Uro-Oncology Research Center of Tehran University of Medical Sciences, Imam Khomeini Hospital, Tehran, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Ayati
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy / Q000379:methods; D051517:Digital Rectal Examination; D006801:Humans; D007610:Kallikreins / Q000097:blood; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D011237:Predictive Value of Tests; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology*; D012372:ROC Curve; D015203:Reproducibility of Results
chemical_list: C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen
keywords: Iran; nomograms; prostate; prostate-specific antigen; validation studies