Linking the National Cardiovascular Data Registry CathPCI Registry with Medicare claims data: validation of a longitudinal cohort of elderly patients undergoing cardiac catheterization.

BACKGROUND: The National Cardiovascular Data Registry CathPCI Registry was recently linked with longitudinal Centers for Medicare & Medicaid (CMS) claims data. The degree to which this linked cohort is representative of the overall CathPCI Registry and CMS PCI populations is unknown. METHODS AND
RESULTS: CathPCI Registry records were linked to CMS inpatient claims using indirect identifiers. We examined the degree to which hospitals and patients in the linked cohort are representative of the elderly (≥65 years) CathPCI Registry and CMS populations. From 2004 to 2006, 1492 hospitals filed CMS PCI claims and 663 contributed CathPCI Registry data. Of these hospitals, 643 (97%) were linked across data sources. Compared with all CMS PCI hospitals, the linked data set contained fewer governmental, northeastern, southern, and low-volume (<200 beds) sites. Among CMS beneficiaries, 993,351 PCI procedures were performed, including 398,508 (40.1%) at centers in the linked database. Of these, 341,916 (86%) were linked to CathPCI Registry records. Linked and unlinked CMS patients had similar demographic and clinical features. In the CathPCI Registry database, 477,456 elderly patients underwent PCI, with 359,077 (75%) linked to CMS claims. Linked and unlinked National Cardiovascular Data Registry patients were similar, except for less commercial or health maintenance organization insurance in the linked cohort.
CONCLUSIONS: By using deterministic matching strategies, a large and representative cohort with detailed clinical data from the CathPCI Registry and longitudinal follow-up from CMS claims has been created.