“…Umeda et al have proposed the appropriate extent of lymphadenectomy in surgery for intrahepatic cholangiocarcinoma according to tumor location, by a multicenter data analysis of the therapeutic index of 279 patients (DOI:10.1002/ags3.12631) 1 . By a multicenter retrospective cohort study of 1,623 patients followed by propensity score matching (PSM), Nakatsutsumi et al have revealed that the prophylactic use of negative‐pressure wound therapy with delayed sutures was associated with a lower incidence of incisional surgical site infection after emergency laparotomy for colorectal perforation 2 . If the number of subjects is large, PSM can be used to adjust background factors and obtain reliable results with scientifically valid analyses.…”