Recursive partitioning for risk stratification in men undergoing repeat prostate biopsies

BACKGROUND. The current study was performed to identity risk factors and risk groups for carcinoma detection in men undergoing repeat prostate biopsies. METHODS. The medical records of all men who had a negative initial prostate biopsy and underwent at least one repeat biopsy between 1992 and 2003 were reviewed to extract age, race, family history of prostate carcinoma, body mass index, referral indication, all prostate-specific antigen (PSA) values, digital rectal examination, PSA density (PSAD), the presence of a hypoechoic lesion, and the presence of high-grade prostatic intraepithelial neoplasia (HGPIN) on initial biopsy. Risk factors for a subsequent diagnosis of prostate carcinoma were identified using the log-rank test and a stepwise, stratified Cox regression model. Based on the risk factors identified by Cox regression analysis, recursive partitioning was further used for risk stratification. RESULTS. A total of 373 patients underwent 975 biopsy procedures. During a median follow-up of 37.0 months, prostate carcinoma was detected in 107 of 373 patients (28.9%). Independent predictors of a positive biopsy (P < 0.05) were PSA doubling time (PSADT), PSAD, referral indication, the presence of HGPIN, patient age, and family history of prostate carcinoma. Recursive partitioning identified 4 distinct risk groups that were characterized by their PSADT and PSAD and the presence of HGPIN and had estimated 2-year and 5-year carcinoma detection rates of 3 ± 1% and 21 ± 4%, 28 ± 5% and 40 ± 7%, 22 ± 6% and 58 ± 8%, and 66 ± 9% and 100%, respectively. CONCLUSIONS. The authors identified a series of independent risk factors for prostate carcinoma detection after an initial negative prostate biopsy and characterized clinically meaningful and distinct patient risk groups. Despite a negative initial biopsy, patients with high-risk features remain at risk for the detection of prostate carcinoma.