NGF and Bartsocas-Papas syndrome 1: In the selected studies, the level of NGF/Cr was significant higher in BPS/IC patients when compared with controlled participants (WMD = 0.96, 95 % CI 0.58–1.35; z = 4.89, P < 0.01), Fig. 3 showed the difference of NGF/Cr level in BPS/IC group and controlled group.