A large body of international outcomes research has documented significant variation in the results of health care, beyond differences attributable to patient age, comorbidity or chance. Naturally, quality of care, however measured, may vary by provider within a health care system. Yet detailed understanding of the relationship between quality of care and health care outcomes continues to elude researchers. Much research has focused on the patient level, determining which patient-focused clinical processes deliver the best outcomes. By contrast, there is a relative lack of research examining intermediate and higher levels, to understand team performance and how teams work to provide high quality care, though research in this area is growing. This thesis aims to develop a greater understanding of how the best colorectal surgical units may be identified, and how they achieve their results.

Chapter 1 provides background to the present approach to the assessment of performance in health care. Chapter 2 summarises salient surgical outcomes research, and chapter 3 presents a literature review of evidence associating specific organisational structures and processes with clinical outcomes. Chapter 4 presents a patient questionnaire study, undertaken to assess the involvement of patients with gastrointestinal cancer in choosing a provider, and what provider-level information patients consider important. Chapters 5 to 8 describe the methods and results of a series of studies using routine administrative data to explore changes within colorectal surgery over time, as well as the relationship between different outcome measures at the unit level. Chapters 9 to 12 present research designed to understand how units achieve their results. This work included developing a semi-structured interview to better understand the key organisational factors determining length of stay after elective colonic surgery. Chapter 13 summarises the main findings and limitations of this thesis, and discusses its implications for practice and future research.