Development of a New Diagnostic Tool (LUTS/BPH Score) for Male Lower Urinary Tract Symptoms Due to Benign Prostatic Hyperplasia.

Purpose: To develop a new diagnostic tool, the LUTS/BPH score, for male lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia (BPH), which integrates the International Prostate Symptom Score (IPSS), prostate size, and urinary flow rate.

Materials and methods: From an initial pool of 75,199 subjects, 12,891 patients met the inclusion criteria. For the statistical analysis used to develop the new LUTS/BPH score, data were refined through outlier removal, normalization, and the collection of relevant variables. Weights for the relevant variables were determined using principal component analysis (PCA).

Results: The new LUTS/BPH score was developed using the three variables: IPSS, prostate size, and maximum urinary flow rate (Qmax). The LUTS/BPH score was calculated by normalizing these variables and applying PCA to determine the weights, resulting in weights of 0.62 for IPSS, -0.64 for Qmax, and 0.46 for prostate size (PCA score=0.62×IPSS -0.64×Qmax+0.46×prostate size). To simplify the LUTS/BPH score calculation in practice, weights were adjusted using IPSS as the reference variable (weight set to 1) and rounded to the first decimal place. The final LUTS/BPH score formula is "LUTS/BPH score=IPSS-Qmax+0.7×prostate size". Based on this distribution, the LUTS/BPH score can classify symptom severity into three categories: (1) Mild symptoms <2, (2) Moderate symptoms: 2-42, and (3) Severe symptoms ≥43.

Conclusions: The newly developed LUTS/BPH score is an objective and quantifiable diagnostic tool for male LUTS due to BPH, supplementing the currently used IPSS with additional key diagnostic indicators such as prostate size and urinary flow rate.