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.