Aim and Objectives
Surgical Quality Assurance (SQA) influences outcome measures in randomised controlled trials (RCTs). The aim of this thesis was to develop and implement an objective and reliable SQA process within an RCT. The objectives were (1) to develop a robust method for standardisation, (2) to design a competency assessment process for credentialing expertise, and (3) to implement SQA and evaluate barriers in the COLOR III trial. COLOR III is an international multicentre RCT comparing transanal total mesorectal excision (TaTME) with laparoscopic approach for rectal cancer.

Method
A multimethod approach was applied to thoroughly address the study aim. In order to address objective 1, a hierarchical task analysis and 4-round Delphi methodology was applied for standardisation of TaTME. For objective 2, a competency assessment tool (CAT) was developed and its validity and reliability were examined with generalisability theory. Lastly, objective 3 was investigated by implementing SQA in COLOR III. Semi-structured interviews and questionnaires were used to examine the effectiveness of SQA and barriers to implementation.

Results
Standardisation was achieved including an operative guide for TaTME. CAT has a matrix of 9 steps and 4 performance qualities; it was shown to be valid and reliable with an overall G-coefficient of 0.883. The SQA system was implemented in COLOR III and barriers of implementation were evaluated. Within the scope of this process a number of mitigating solutions were identified.

Conclusion
A rigorous iterative approach was applied to develop an objective, and reliable SQA system within a large international multicentre RCT. This system is implemented within the scope of COLOR III and comprises operative guide of standardised TaTME, an objective CAT, defined criteria for trial entry, and a process for monitoring surgical performance during the trial. This PhD serves as a blueprint for the design of SQA in future surgical RCTs.