Dichotomous estimation of prostate gland volume to inform treatment for benign prostatic hyperplasia: a prospective diagnostic study of the accuracy of digital rectal examination Introduction Accurate estimation of prostate size on DRE is an important tool for assessing risk of progression to benign prostatic hyperplasia and selection for 5-alpha reductase inhibitor (5- ARI) therapy. Previous studies have shown that despite underestimation of TRUS measured volumes DRE estimates have a role in distinguishing sizes larger than a given cutpoint 1. Recent investigations have demonstrated the high positive predictive value of DRE when used to identify patients with volumes greater than 30cc and were suitable for 5-ARI therapy 2. Conclusions DRE is a reliable tool for dichotomous assessment of prostatic volumes above 30 and 50cc. These results illustrate the value of re-examining the role of categorical DRE estimations in BPH patients. Results Patient characteristics Our population base presented for investigation of LUTS and biopsy. Patients that agreed to participate in this procedure had a range of characteristics displayed in Table 1. Table 1: Study population characteristics The high average PSA level was consistent with the large proportion of patients who presented for suspected prostate cancer. Figure 1: Diagnostic score values for three separate cut-offs At a 50cc cut-off positive predictive value was 81.1% (95%CI 73.3 – 87.4) compared to 94.3% (95%CI 90.6 – 96.8) for 30cc cut-off estimates. Specificity improved when estimating sizes greater than 50cc (84.76%, 95%CI ) compared to 30cc (76.27%, 95%CI 78.3 – 89.9). Mean PSA level (microg/L) for prostates less than 50cc (6.27) and more than 50cc (11.82) was comparable to grade 0-1 (6.89) and grade 2-3 (11.57) estimations. Figure 2: ROC curves with area under curve calculations Methods Patient selection A total of 303 patients presenting to a single tertiary centre practice were prospectively recruited between January 2010 and August Measurements Patients were examined by either a urologist or senior urology trainee. Each patient was graded to one of four groups: 100cc. These results were compared to gold-standard TRUS volume measurements based on three dimensional measurements (transverse, anterior-posterior and sagittal length). Patients also had WHO International Prostate Symptoms Score (IPSS) and serum total PSA levels measured prospectively. Outcomes Primary outcome was positive predictive value and specificity of DRE measurements for greater or less than 50cc. Secondary outcomes were positive predictive value and specificity of DRE measurements at a 30cc cut-off and mean serum PSA levels for each group. Analysis Diagnostic performance tests and receiver operator curves were calculated using SPSS © Version 20 GradPack software. ROC curves were summarised by discriminative ability and pairwise testing by the DeLong test. Acknowledgements Dr Lenaghan and A/Prof Woo for their rigorous efforts in patient collection, study design and invaluable guidance throughout this project. Aim The following study was designed to examine the reliability of DRE as a simple, minimally invasive and cost-effective tool to provide guidance for clinicians on differentiating between set prostate volume thresholds and to compare its performance to the gold standard TRUS measurements for patients presenting with LUTS. References 1. Roehrborn CG, Girman CJ, Rhodes T, Hanson KA, Collins GN, Sech SM, et al. Correlation between prostate size estimated by digital rectal examination and measured by transrectal ultrasound. Urology Apr;49(4): Ahmad S, Manecksha RP, Cullen IM, Flynn RJ, McDermott TE, Grainger R, et al. Estimation of clinically significant prostate volumes by digital rectal examination: a comparative prospective study. Can J Urol Dec;18(6): Michael Su 1, Daniel Lenaghan 2 & A/Prof Henry Woo 3 1 Westmead Hospital, Sydney, 2 Liverpool Hospital, Sydney, 3 Sydney Adventist Hospital, Sydney Poster presentation sponsor No. 093 Average Age (years)64.90 (34-89) Average IPSS11.86 (0-35) Average QL score2.53 (0-12) Average PSA8.78 (0-140)