Case Example 21Linking a Procedure-Based Registry With Claims Data To Study Long-Term Outcomes

DescriptionThe CathPCI Registry measures the quality of care delivered to patients receiving diagnostic cardiac catheterizations and percutaneous coronary interventions (PCI) in both inpatient and outpatient settings. The primary outcomes evaluated by the registry include the quality of care delivered, outcome evaluation, comparative effectiveness, and postmarketing surveillance.
SponsorAmerican College of Cardiology Foundation (ACCF) through the National Cardiovascular Data Registry (NCDR). Funded by participation dues from catheterization laboratories
Year Started1998
Year EndedOngoing
No. of Sites1,150 catheterization laboratories
No. of Patients8.8 million patient records; 2.91 million PCI procedures


The registry sponsor was interested in studying long-term patient outcomes for diagnostic cardiac catheterizations and percutaneous coronary interventions (PCI), but longitudinal data are not collected as part of the registry. Rather than create an additional registry, it was determined that the most feasible option was linking CathPCI data with available third-party databases such as Medicare.

Before the linkage could occur, however, several legal questions needed to be addressed, including what identifiers could be used for the linkage and whether institutional review board (IRB) approval was necessary.

Proposed Solution

The registry developers explored potential issues relating to the use of protected health information (Federal HIPAA [Health Insurance Portability and Accountability Act] laws) to perform the linkage; the applicability of the Common Rule (protection of human subjects) to the linkage; and the contractual obligations of the individual legal agreement with each participating hospital with regard to patient privacy. The CathPCI Registry gathers existing data that are collected as part of routine health care activities. Informed consent is not required. Direct patient identifiers are collected in the registry, and the registry sponsor has business associates’ agreements in place with participating catheterization laboratories.

After additional consultation with legal counsel, the registry sponsor concluded that the linkage of data could occur under two conditions: (1) that the datasets used in the merging process must be in the form of a limited data set (see Chapter 8), and (2) that an institutional review board must evaluate such linkage. The resulting decision was based on two key factors: First, the registry participant agreement includes a data use agreement, which permits the registry sponsor to perform research on a limited data set but also requires that no attempt be made to identify the patient. Second, since there was uncertainty as to whether the proposed data linkage would meet the definition of research on human subjects, the registry sponsor chose to seek IRB approval, along with a waiver of informed consent.


CathPCI Registry data were linked with Medicare data, using probabilistic matching techniques to link the limited datasets. A research protocol describing the need for linkage, the linking techniques, and the research questions to be addressed was approved by an IRB. Researchers must reapply for IRB approval for any new research questions that they wish to study in the linked data.

Results of the linkage analyses were used to develop a new measure, “Readmission following PCI,” for the Centers for Medicare & Medicaid Services hospital inpatient quality pay-for-reporting program. The new measure is currently under review.

Key Point

There are many possible interpretations of the legal requirements for linking registry data with other data sources. The interpretation of legal requirements should include careful consideration of the unique aspects of the registry, its data, and its participants. In addition, clear documentation of the way the interpretation occurred and the reasoning behind it will help to educate others about such decisions and may allay anxieties among participating institutions.

For More Information

  1. National Cardiovascular Data Registry: CathPCI Registry. Available at https://www​​/webncdr/DefaultCathPCI.aspx. Accessed June 17, 2010.

From: Chapter 7, Linking Registry Data: Technical and Legal Considerations

Cover of Registries for Evaluating Patient Outcomes: A User's Guide
Registries for Evaluating Patient Outcomes: A User's Guide. 2nd edition.
Gliklich RE, Dreyer NA, editors.

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