Estimating the number of coronary artery bypass graft and percutaneous coronary intervention procedures in Canada: A comparison of cardiac registry and Canadian Institute for Health Information data sources

BACKGROUND: Provincial cardiac registries and the Canadian Institute for Health Information (CIHI) pan-Canadian administrative databases are invaluable tools for understanding Canadian cardiovascular health and health care. Both sources are used to enumerate cardiovascular procedures performed in Canada. OBJECTIVE: To examine the level of agreement between provincial cardiac registry data and CIHI data regarding procedural counts for coronary artery bypass grafts (CABGs) and percutaneous coronary interventions (PCIs). METHODS: CIHI staff obtained CABG and PCI counts from seven provinces that, in 2004, performed these procedures and had a cardiac registry (ie, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Nova Scotia, and Newfoundland and Labrador). Structured mail questionnaires, and e-mail and telephone follow-ups elicited information from a designated registry respondent. The CIHI derived its counts of CABG and PCI procedures by applying the geographical boundaries, procedural definitions and analytical case criteria used by the cardiac registries to CIHI inpatient and day procedure databases. Steps were taken to reduce double-counting procedures when combining results from the two CIHI databases. Two measures were calculated: the absolute difference between registry and CIHI estimates, and the per cent agreement between estimates from the two sources. RESULTS: All seven cardiac registries identified as eligible for the study participated. Agreement was high between the two sources for CABG (98.8%). For PCI, the level of agreement was high (97.9%) when CIHI sources were supplemented with day procedure data from Alberta. CONCLUSIONS: The high level of agreement between cardiac registry and CIHI administrative data should increase confidence in estimates of CABG and PCI counts derived from these sources.