Predictors of pain improvement with Kampo formulas after UPOINT-guided management in chronic pelvic pain syndrome: a retrospective cohort study.

Objectives: Chronic prostatitis or chronic pelvic pain syndrome is a heterogeneous condition commonly managed using the symptom-based Urinary, Psychosocial, Organ-specific, Infection, Neurologic/Systemic, and Tenderness (UPOINT) system; however, pain often persists despite targeted treatment. This study evaluated the effectiveness of traditional Japanese Kampo formulas as an additional therapy and sought to identify the clinical predictors of pain improvement in affected patients. Methods: We retrospectively analyzed 71 patients with chronic prostatitis or chronic pelvic pain syndrome who were treated according to the UPOINT system at a university hospital between May 2021 and January 2025. Among them, 37 received Kampo formulas in addition to standard therapy, while 34 received standard therapy alone. Outcomes were assessed using validated symptom questionnaires measuring prostatitis, urinary, and overactive bladder symptoms, and general health status. Changes in scores were compared between the groups, and multivariable logistic regression analysis was performed to identify the independent predictors of pain improvement associated with Kampo treatment. Results: Patients who repeatedly received Kampo formulas experienced penile or scrotal pain, and prostatic tenderness was elicited on examination; however, urinary symptoms were relatively mild. The Kampo group demonstrated a significantly greater improvement in pain scores than the standard therapy group, whereas improvements in urinary symptoms and quality of life were similar between the groups. Prostatic tenderness and pain-dominant symptoms were independently associated with pain improvement. No severe treatment-related adverse events were observed. Conclusion: Kampo formulas may provide effective additional pain relief for selected patients, particularly those with prostatic tenderness and predominant pain symptoms, thereby supporting more individualized treatment strategies. However, these findings should be interpreted with caution because of the retrospective study design, small sample size, baseline imbalances between the groups, and potential residual confounding related to the non-randomized selection of Kampo treatment. Prospective randomized studies are warranted to confirm these findings.