Combined anatomical parameters predict benign prostatic hyperplasia-related lower urinary tract symptom severity: a volume-stratified study.

Abstract

Background: The association between prostate volume (PV) and lower urinary tract symptoms (LUTS) in benign prostatic hyperplasia (BPH) is inconsistent, as significant symptoms frequently occur even with small prostates. Although ultrasonography noninvasively ascertains anatomical parameters, such as intravesical prostatic protrusion (IPP) and bladder neck angle (BNA), their predictive value across different prostate sizes remains unclear. We aimed to examine the association between prostatic anatomical parameters and the severity of LUTS in patients with BPH across different PV categories, and to develop a predictive model for voiding dysfunction based on these anatomical parameters.

Methods: This retrospective study included 257 patients with BPH who visited The First Affiliated Hospital of Jinan University for LUTS between January 2023 and March 2024. Transrectal ultrasound was used to measure the PV, IPP, BNA, prostatic urethral angle (PUA), prostatic urethral length (PUL) and other anatomical parameters. Patients were stratified by PV (<30 vs. ≥30 mL). The International Prostate Symptom Score (IPSS) and maximum urinary flow rate (Qmax) were recorded. Prostatic anatomical parameters were correlated with the LUTS severity using Spearman's rank correlation analysis, followed by linear regression modeling to quantify these associations. Predictive models were constructed based on the parameters identified by logistic regression. Receiver operating characteristic (ROC) curves were utilized to determine optimal cutoff values and evaluate model performance.

Results: Of 257 patients with BPH, 91 (35.4%) and 166 (64.6%) belonged to the large-volume and small-volume groups, respectively. Multivariable linear regression revealed that, in small prostates, PUL (β=0.20), BNA (β=0.12) and age (β=0.11) independently predicted the International Prostate Symptom Score total score (IPSS-t), whereas PUL (β=-0.29) and BNA (β=-0.09) predicted Qmax. For large prostates, IPP (β=0.29), age (β=0.14), BNA (β=0.09), and PUA (β=0.08) predicted IPSS-t, whereas IPP (β=-0.21) and PUA (β=-0.09) predicted Qmax. Logistic regression demonstrated that the combination of IPP, BNA, and PUA constituted a significant predictor of voiding dysfunction (Qmax <10 mL/s) in patients with large PV. In the large-volume group, the combined model achieved an area under the curve (AUC) of 0.94 [95% confidence interval (CI): 0.90-0.99], which indicated robust discriminative power.

Conclusions: Volume-stratified analysis provides a more precise assessment of prostate anatomical parameters in BPH. A model integrating IPP, BNA, and PUA demonstrates favorable accuracy in predicting voiding dysfunction specifically in large‑volume BPH. These findings underscore the clinical utility of ultrasonographic anatomical assessment and support volume‑stratified management. Prospective multicenter validation is required to translate this tool into practice.