Table 1. Classification of complications.

Grade	Definition	Comments
I	Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic and radiological interventions. Acceptable therapeutic regimens: drugs as anti-emetics, antipyretics, analgesics, diuretics and electrolytes and physiotherapy. This grade also includes wound infections opened at the bedside.	Included persistent diarrhoea, nausea or vomiting
II	Requiring pharmacological treatment with drugs other than such allowed for grade I complications. Blood transfusions and total parenteral nutrition are also included.	The need for blood transfusion alone was not included as a complication here
III	Requiring surgical, endoscopic or radiological intervention
IIIa	Intervention not under general anesthesia
IIIb	Intervention under general anesthesia
IV	Life-threatening complication (including CNS complications) requiring IC/ICU-management	Included blood pressure instability requiring transfer to high-dependency
IVa	Single organ dysfunction (including dialysis)
IVb	Multi organ dysfunction
V	Death of a patient	Excluded here as deceased patients unable to be surveyed

Above classifications based on the Clavien-Dindo Classification [17].