This study was to designed to measure the true worldwide practice of liver surgery and associated outcomes by recruiting multiple international centres, committing to consecutive patient registration per surgeon and undergo rigorous data validation. It is hoped that these data will provide a more appropriate guide to inform surgeons and patients to assess which level of complexity should be routinely offered for high tumour burden and anatomically difficult scenarios.

Liver surgery was associated with at least 10% mortality in the 1970's. The safety of liver surgery has dramatically improved since with a mortality of now around 1-2%. Individual centres postulate that a perioperative mortality close to 0% should be the standard of major liver resection. Despite these claims, epidemiological studies showed a mortality rate of 6%. Outcomes in liver surgery are likely influenced by indications, complexity, centre and surgeon skills, equipment, centre and surgeon experience. The aim of LiverGroup.org is to develop an international data set on the outcomes of liver resections among a large number of international surgeons. The 'collaborative' model for 'snapshot' clinical audit is now well established and such research is a novel approach for assessing current practice in a short period of time. The primary objective of the study is to provide a verified record of the true perioperative morbidity and mortality of a representative set of liver surgeons worldwide in 2019. Secondary objectives include risk factors for mortality and morbidity using multivariable regression models. Any surgeon performing liver resections is eligible to participate in LiverGroup.org. All consecutive cases will be included and there are no minimum patient numbers per centre. Liver transplantation is excluded. There will be 3 months of prospective patient enrolment and 3 months follow up within the 12-month frame, January to December 2019. All liver resections, all indications, as well as all co-morbidities will be included. Liver transplantation, imaging-guided ablations and liver biopsies are excluded.

Inclusion Criteria:

• All indications (including benign and living donor resections)
• All co-morbidities
• Open, laparoscopic or robotic
• Single wedge resections to extended liver resections
• Single or two-stage hepatectomies
• Procedures with liver volume enhancement such as PVE, PVL, ALPPS.
• Resections involving cold perfusion (ex-situ and ante-situ)
• There are no exclusion criteria as related to indication, age or comorbidities.

Exclusion Criteria:

• Liver transplantation
• Imaging-guided liver ablation techniques alone
• Liver biopsies

Any adult patient undergoing liver surgery.

The datasets generated and analysed during the current study will be available upon request from the Management Committee of LiverGroup.org. The study Primary Investigators will act as the custodians of the data. The data, however, belong to all collaborators. The Steering and Management committees together will decide after the publication of the main report about requests regarding secondary analysis and will consider all such requests based on quality and the validity of the proposed project and decide by majority decision. All data provided will be fully anonymized without any patient identifiers.

The data will become available after the completion and publication of the first study generated by LiverGroup.org

The steering and management committees together will decide after the publication of the main report about requests regarding secondary analysis and will consider all such requests based on quality and the validity of the proposed project and decide by majority decision.