Annelotte van Bommel

10 GENERAL INTRODUCTION AND OUTLINE OF THIS THESIS Systematically monitoring treatment outcomes was first described over a century ago by Ernest A. Codman. In his view, the results of every treated case ought to be registered and at all times accessible for evaluation by members of the staff, trustees, administration or other authorized investigators. In his time, evaluating and improving healthcare by reflecting on actively collected outcome data was a progressive thought. 1 Today, many have adopted the view that evaluating care by the analysis of outcomes of treated patients is an important step in the “Plan Do Check Act (PDCA)” cycle to improve healthcare quality. 2 Clinicians, hospitals, and countries have collectively embraced clinical auditing and adhere to the concept of systematically measuring and subsequently improving quality of care. While individual professionals and institutions aim to evaluate and improve their own performances in relation to peers, society calls for transparency of the quality of care to enable patients to choose a healthcare provider based on reliable information. Other stakeholders such as healthcare insurance companies and the healthcare inspectorate also demand transparency of the quality of care given in hospitals. In the Netherlands, nationwide clinical auditing on an institutional level was catalyzed by the increased interest of the national healthcare inspectorate (IGJ) 3 in the relationship between hospital volume and outcomes of surgical care at the beginning of the 21 st century. Following the nationwide query of the institutional volume of esophageal surgery in 2006 and the publication of institutional rates of tumor positive margins in patients undergoing breast conserving surgery in 2008, 3,4 nationwide clinical auditing was swiftly implemented for several surgical oncological disorders. The Initiation of a National Breast Cancer Audit in the Netherlands The National Breast Cancer Organization Netherlands (NABON) was established in 1999 to improvemultidisciplinary care for breast cancer patients, an initiative started by clinicians. 5 Initially, NABON pursued publishing national treatment guidelines