Elevation of serum c‐reactive protein in patients with OAB and IC/BPS implies chronic inflammation in the urinary bladder

Chronic inflammation has been implicated in the development of overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS). An elevation of C-reactive protein (CRP) has been associated with chronic inflammation and lower urinary tract symptoms. This study aims to elucidate the association between CRP and OAB or IC/BPS.Serum CRP and urinary nerve growth factor (NGF) levels were examined in 70 patients with OAB (n=22) or IC/BPS (n=48) and compared with 33 normal controls. Data of serum CRP and urinary NGF levels were compared among the controls, IC/PBS, and OAB. The Spearmen correlation analysis test and ANOVA (Kruskal-Wallis) test were used for statistical analysis with P<0.05 considered significant.Serum CRP levels were significantly higher in subjects with OAB (1.83 ± 2.30 mg/L vs. 0.59 ± 0.40 mg/L, P=0.012) or IC/BPS (1.76 ± 3.56 mg/L vs. 0.59 ± 0.40 mg/L, P=0.049) than in controls. No significant difference in CRP level was noted between patients with OAB and IC/BPS (P=0.43). In a subgroup analysis, patients of OAB wet had higher serum CRP level than that of OAB dry (2.95 ± 3.08 mg/L vs. 0.90 ± 0.52 mg/L); however, the difference did not reach statistical significance (P=0.34). The CRP between OAB wet and OAB patients with medical disease was not significantly different. There was no significant correlation between serum CRP and urinary NGF levels in the controls or patients with OAB or IC/BPS, except in the OAB patients with a CRP level >3 mg/L.Our data support the association between chronic inflammation of the urinary bladder in patients with OAB or IC/BPS.