What is the key piece of data needed to link a patient seen in various care settings?

The key piece of data needed to link a patient seen in various care settings is the identity matching algorithm. This algorithm serves as a method for accurately matching and linking patient records across different healthcare facilities and information systems. Given that patients may have different identifiers or records in various settings, an identity matching algorithm relies on a combination of data points, such as names, birth dates, and other demographics, to ensure that records are accurately connected to the same individual, despite differences in how that information may be housed or formatted in different systems.

The algorithm enhances record accuracy by reducing the risk of mismatches, thereby improving patient safety and continuity of care. While other options like facility medical record numbers or patient birth dates might contribute to the identification process, they do not establish a comprehensive linking system across diverse electronic health record systems, which the identity matching algorithm effectively facilitates.