Evaluating the implications of clinical practice guidelines for patient care.

Patient care evaluation studies have been developed by the Commission on Cancer of the American College of Surgeons. The studies were primarily designed to monitor trends in diagnosis, therapy, and outcome of specific oncologic diseases in hospitals and cancer centers. As they reflect the current standards of patient care, patient care evaluation studies have become valid tools of quality management in medicine. In an international pilot project that began in 1996, this approach was redefined to evaluate the impact of current clinical practice guidelines in oncology. Close cooperation between medical societies in the United States and Germany under the coordination of the Commission on Cancer and the Institute of Medical Informatics at the Justus-Liebig-University of Giessen was established. This infrastructure for data collection, data management, analysis, and interpretation of results allows for the recognition of international differences in patient care. Our results indicate discrepancies between current state-of-the-art patient care represented by clinical practice guidelines and the diagnostic and therapeutic procedures in the clinical routine. Patient care evaluation studies are designed as exploratory, not confirmatory, trials. In contrast with confirmatory trials, their aims may not always lead to predefined hypotheses. They reflect routine practice and are not the basis of the formal proof of efficacy, although they may contribute to the total body of relevant evidence. Without this comprehensive approach to evaluation, the potential of clinical practice guidelines to improve patient care remains unknown.