External validation of the prostatic inflammation nomogram to predict prostatic inflammation in men with lower urinary tract symptoms

Background: Recently a nomogram has been developed to predict prostatic inflammation. Aim of our study is to validate the prostatic inflammation nomogram (PIN) for predicting the presence of prostatic inflammation in men with lower urinary tract symptoms (LUTS). Methods: A consecutive series of men (≥40 years) with benign prostatic hyperplasia (BPH)/LUTS scheduled for prostatic surgery or transrectal ultrasound-guided (TRUS) prostate biopsy were enrolled. The presence of inflammation in the prostatic tissue samples, assessed according to the Irani score, was determined. Inflammation was classified using the Irani score into two categories: 0-2 (no/minimal inflammation) and 3-6 (moderate/severe inflammation). The discrimination, calibration, and net benefit of the nomogram were evaluated. Results: A total of 429 patients (mean age 70 years) were recruited. Overall, 257/429 (60%) presented with prostatic inflammation. On multivariable binary logistic regression analysis diabetes mellitus (OR=2.28; P=0.006), higher storage International Prostate Symptom Score score (OR=1.17; P<0.001), a prostate volume greater than 50 mL (OR=2.14; P<0.001), a positive urine dipstick test for leukocytes (OR=4.37; P<0.001) and a history of previous urinary tract infections (OR=2.34; P<0.001) were predictors of inflammation. Receiver operating characteristic analysis showed the nomogram with an AUC of 0.76 (95% CI: 0.72-0.81). Calibration was fair, and the nomogram demonstrated clinical net benefit within a probability range of 30% to 85%. Conclusions: The PIN nomogram showed good predictive ability and net benefit. Its use may help individualize treatment for LUTS by identifying candidates for therapies targeting prostatic inflammation.