The main objective of the proposed project is to develop and to validate a system for measurement and feedback of outcome quality and support of decision making. The project will be executed in the areas of postoperative pain management which serves as an example for other fields of medicine with a high variation of care. The project will provide the medical community with a unique, user-friendly system to improve treatment of patients with postoperative pain. We propose to develop and implement a web-based information system, featuring three functions: Feedback and benchmarking system which provides participating sites with continuously updating data and analyses about the quality of care they provide compared to other institutions and allows identification of ‘best clinical practice’. Clinical Decision Support System for Post-Operative Pain, which responds to queries made by physicians for advice regarding treatment of individual patients. A Knowledge Library which provides clinicians with easily accessible summaries of evidence-based recommendations tailored to specific post-operative situations. The first two functions will draw their information from a large database or registry. The registry will receive data about post-operative patients from x participating clinical sites across Europe. The third function, the Knowledge Library, will draw its information from published, peer-reviewed studies, and will be updated periodically. To increase the benefit of the system to end-users, the registry will be complemented with patient data on side effects and treatment costs. All of these will be integrated into the feedback system. The proposed project is the first comprehensive, concerted European effort in the field of improving clinical decision making. It integrates experience gained from national initiatives, and the expertise of world-leading, European-based, groups dealing with benchmarking, health outcomes and health care utilization research