Witzigmann 2016

Methods	Randomized controlled trial.
Participants	Country: Germany. Number randomized: 438. Postrandomization dropout: 43 (2.2%). Mean age: 63.4 years. Females: 139 (35.2%). Pancreatic cancer: 159 (40.3%). Biliary cancer: 23 (5.8%). Duodenal cancer: 5 (1.3%). Ampullary cancer: 19 (4.8%). Chronic pancreatitis: 101 (25.6%). Pancreaticoduodenectomy: 328 (83.0%). Distal pancreatectomy: 0 (0%). Other pancreatic surgery: 67 (17.0%). Inclusion criteria: Aged ≥ 18 years. People planned for pancreatic head resection with pancreaticojejunal anastomosis for benign or malignant tumours, chronic pancreatitis, or other indications. Exclusion criteria: People who underwent extended resection. People who had a cardiac infarction within 6 months before operation. Malignancy that has not responded to treatment within 5 years before operation. Lack of compliance. Pregnancy or lactation. Participation in another trial with interference of intervention or outcome.
Interventions	Participants (N = 395) were randomly assigned to 1 of 2 groups. Group 1: drainage (N = 202). Group 2: no drainage (N = 193).
Outcomes	Mortality, morbidity, wound infection, intra‐abdominal infection, various postoperative complications, reoperation, operation time, and length of hospital stay.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "A random list was created by GWT‐TUD Ltd".
Allocation concealment (selection bias)	Low risk	Quote: "The random allocation sequence was implemented by the use of sequentially numbered opaque envelopes".
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: no information provided.
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "A total of 438 patients were randomized. Forty‐three patients (9.8%) were excluded because no pancreatic resection with consecutive pancreaticojejunal anastomosis was performed. Thus, the intention‐to‐treat population consisted of 395 patients". Comment: there are 43 postrandomization dropouts. The study did not perform an intention‐to‐treat analysis which included the 43 dropouts.
Selective reporting (reporting bias)	Low risk	Comment: the study protocol was available. All of the study's prespecified outcomes were reported.
Other bias	Low risk	Comment: the study appeared to be free of other sources of bias.

IU: international unit; N: number of participants.