An External Validation And Comparison Of The Predictive Accuracy Of Four Models Designed To Predict The Probability Of A Positive Prostate Biopsy

Objective: To validate and compare the predictive accuracy of four prostate cancer models designed to predict the likelihood of a positive initial transrectal biopsy.Methods: Data of 813 consecutive patients between January 2010 and September 2014 who had undergone a TRUS-guided prostate biopsy at our institution were reviewed, 431 patients fulfilling all criteria for four predictive models were enrolled for the final analysis. The risk of each individual positive biopsy was calculated using either of the four models. The predictive accuracy of each model was measured using area under the receiver operating characteristic curve(AUC), and the comparison of AUCs was performed by z test.Results: Of 431 participants, the statistical analysis of age, prostate-specific antigen(PSA), digital rectal examination(DRE), prostate volume and transrectal ultrasound(TRUS) findings were all significantly different, except percentage of free prostate-specific antigen(%fPSA)(P =0.242). AUCs were 0.774(95%CI, 0.726~0.822), 0.765(95% CI, 0.714~0.816), 0.813(95% CI, 0.767~0.858), 0.795(95% CI, 0.749~0.842) and 0.736(95% CI, 0.684~0.788) for the North-American Prostate Cancer Prevention Trial Derived Cancer Risk Calculator(PCPT-CRC) model, Montreal model, domestic model 1, domestic model 2 and PSA alone, respectively. There was no significant difference among AUCs of the four models, and a 7.7% increased predictive accuracy was observed for the domestic model 1 compared to unlimited PSA alone(P< 0.05). When serum PSA ranging from 4 to 10 ng?ml-1, AUCs were 0.688(95% CI, 0.560~0.816), 0.818(95% CI, 0.719~0.918), 0.830(95% CI, 0.740~0.919), 0.853(95% CI, 0.771~0.935) and 0.565(95% CI, 0.419~0.710) for the four models and PSA alone,respectively. Domestic model 2 owned the highest predictive accuracy and a 28.8% increased predictive accuracy was observed for the domestic model 2 compared to PSA alone(P< 0.05).Conclusions: External validation and comparison of the four models reveals that all of the four models have acceptable predictive accuracy in our cohort. There is no difference of predictive accuracy between foreign and domestic models according to the AUC results. However, domestic model 1 is superior to unlimited PSA alone, and domestic model 2 has the highest predictive accuracy when serum PSA ranging from 4 to 10 ng?ml-1.