Early cholecystectomy following percutaneous transhepatic gallbladder drainage is effective for moderate to severe acute cholecystitis in the octogenarians

•For patients aged ≥ 80 years with moderate to severe acute cholecystitis, the morbidity and mortality rates of cholecystectomy are not high.•Early cholecystectomy (< 6 weeks) and delayed cholecystectomy (≥ 6 weeks) have similar rates in conversion surgery, perioperative complications, and operative mortality.•Early cholecystectomy has lower risks of recurrent acute cholecystitis and further biliary events compared with delayed cholecystectomy.