Baseline Neutrophil-to-Lymphocyte Ratio is Associated With Poorer Response to Low-Intensity Shockwave Therapy for Erectile Dysfunction: A Two-Centre Retrospective Cohort

Abstract

Background: Low-intensity extracorporeal shock wave therapy (Li-ESWT) is explored for erectile dysfunction (ED), yet guideline recommendations remain cautious. Simple blood-count ratios such as neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte (PLR) may help identify who benefits. Objective: To evaluate whether baseline NLR/PLR are associated with, and can discriminate, clinical response to Li-ESWT. Methods: Retrospective, two-centre cohort. We analysed 160 men with ED treated with a standardized 12-session Li-ESWT protocol; 100 men without ED (5-item International Index of Erectile Function [IIEF-5] ≥22) served only for baseline comparisons and were excluded from outcome/prediction analyses. Erectile function (IIEF-5) was recorded at baseline, end of treatment, and Month 6. The primary endpoint was response at Month 6, defined a priori as the minimal clinically important difference (MCID) of ΔIIEF-5 ≥ 4. ROC analyses and multivariable logistic regression were adjusted for age, body mass index (BMI), hypertension, diabetes, and smoking. Preanalytic CBC screening minimized inflammatory confounding. Results: Response occurred in 110/160 (68.8%). NLR was higher in nonresponders than responders and controls (2.27 ± 0.71 vs. 1.63 ± 0.52 and 1.69 ± 0.60; p < 0.001), whereas PLR differences were smaller (p = 0.032). NLR discriminated responders from nonresponders with an AUC of 0.752 (95% CI 0.672–0.831); the Youden-optimal cutoff was 1.93 (sensitivity 72%, specificity 71%; PPV 85%, NPV 54). PLR showed weaker discrimination (AUC 0.610, 95% CI 0.520–0.701). In multivariable models, baseline NLR (per 1-SD) independently predicted nonresponse (OR 2.80, 95% CI 1.70–4.62; p < 0.001), while PLR did not (OR 1.25, 95% CI 0.83–1.89; p = 0.29). Hypertension was also associated with nonresponse (OR 3.74, 95% CI 1.43–9.77; p = 0.007). Conclusions: In this two-centre cohort, baseline NLR, measured on routine CBC, was associated with Li-ESWT nonresponse and provided moderate discrimination, whereas PLR performed weakly. NLR may support pretreatment risk-stratification, but prospective, sham-controlled validation and external threshold calibration are needed before clinical adoption.