Understanding the member population to which medical coverage policies apply is important for ensuring the relevance of a health insurer's policies. The medical policy unit of our company developed a registry and workflow to enhance our knowledge about the members who seek authorization for bariatric surgery. Data captured in the registry have allowed us to construct a descriptive profile of the entire population that seeks bariatric surgery (both members who are approved and members who are denied). In addition, we have examined characteristics associated with denied authorization requests, determined the proportion of requests originating from specific insurance products, and studied the relationship between results on a specific laboratory test and authorization decisions. Given the growing importance of data in the realm of health care management, this article is an important demonstration of how data can be used to understand populations of members who are affected by medical policies. and medical policies, with each insurer developing its own companyspecific policies. It is essential that medical coverage policies be written in a manner that promotes the best health for insured members while aligning with the mission of a company. Sometimes, there is insufficient evidence on a new procedure or drug to know for sure which patients will benefit from it most and which may not benefit at all.As part of an academic health system, our organization strives to maximize the knowledge obtained from data we collect. Current research in the industry relies heavily on administrative claims 1,2 that are useful for providing data about use and costs. However, there are other sources of information that can be informative to medical policy decisions that remain largely untapped. Claims data do not contain information that is submitted as part of pre-authorization requests (such as clinical measurements and laboratory values). Additionally, data from claims do not contain information about members who were denied authorization for a procedure. A source of data beyond claims can be helpful for providing a more complete profile of a member population seeking services. We are currently working to expand knowledge at the juncture between the medical-policy setting and the subset of members who are affected by coverage decisions. The mechanism we have chosen to increase our knowledge in this area is the development of registries.The need for a registry to record member-level information surrounding certain procedures first became apparent, as the medical policy unit at our company planned a revision to the coverage policy for bariatric surgery. Anecdotal stories and opinions about bariatric surgery were prevalent, but no one was able to provide information derived from an aggregate collection of authorization requests.To address the uncertainty about details contained in requests for bariatric surgery, we developed a registry of bariatric surgery requests containing data to inform future policy decisions. The registry r...