A patient registry is defined as "an organized system that uses observational study methods to collect uniform data (clinical and other) to evaluate specified outcomes for a population defined by a particular disease, condition, or exposure. A registry also serves one of more predetermined scientific, clinical, or policy purposes." Patient registries may be used for a variety of purposes, including one or more of the following: effectiveness research for drugs or devices, natural history of disease, post-marketing commitments or safety monitoring, quality improvement programs, certification programs (e.g., for physicians to retain membership in a professional medical organization), and surveillance programs (e.g., to track vaccination status).