Elevated level of nerve growth factor in the bladder pain syndrome/interstitial cystitis: a meta-analysis

OBJECTIVES: To elucidate the association between nerve growth factor (NGF) level and bladder pain syndrome/interstitial cystitis (BPS/IC) by conducting a meta-analysis. METHODS: We conducted a systematic literature search to identify original studies of NGF level in BPS/IC before November 2015. Eligible studies were retrieved via both computer searches and manual review of references. The summary difference estimates between controlled group and BPS/IC group were calculated based on the weighted mean difference (WMD) with its 95 % confidence interval (CI). Sensitivity and publication analyses were performed after the pooled analysis. RESULTS: Meta-analysis of 10 original studies involving 295 cases and 290 normal controls showed an increased level of urinary NGF in BPS/IC patients (z = 3.08, P = 0.002). The combined WMD was 36.39 (95 % CI 13.27–59.51). There was significant difference between controlled group and BPS/IC patients in the term of NGF/Cr level (WMD = 0.96, 95 % CI 0.58–1.35; z = 4.89, P < 0.01). There was no significant publication bias in the included studies (P for Begg’s test = 0.73, P for egger’s test = 0.13). CONCLUSIONS: Our results demonstrated that there was an increased level of NGF in the BPS/IC patients.