Using data linkage to identify First Nations Manitobans: technical, ethical, and political issues.

BACKGROUND The Manitoba Health Registry does not fully identify First Nations Manitobans, impacting the ability to adequately describe their health status and use of health services using this data source alone. This paper describes the processes in producing a valid database for use in a population-based report by the Manitoba Centre for Health Policy (MCHP). METHODS The Indian Registry's Status Verification System (SVS) file is a national database containing a complete list of Registered First Nations eligible for benefits through the Indian Act. Through negotiations with the Assembly of Manitoba Chiefs' Health Information Research Committee, Indian and Northern Affairs Canada, FNIHB, Manitoba Health, and MCHP, a linkage of the SVS files and Manitoba Health's Registry was accomplished. Of the 116,177 SVS records and 5,803 deceased records, 97,635 individuals linked to the Manitoba Health Registry. RESULTS There was a 99% match on gender, 70% match on surname, 94% match on given name, and 96% match on birth year. The total represents a 20% decrease in records from the Indian Registry. The decrease was greater for females, older people and those from southern areas. CONCLUSION The linkage resulted in a 20% increase over Manitoba Health data alone. Our inability to link all of the records may be due to several factors. Individuals with a Manitoba Band affiliation living outside of the province could not be linked to the Manitoba Health Registry. First Nations living in Manitoba but affiliated with a non-Manitoba Band would not have been in the file obtained. Finally, births, deaths and surname change after marriage may be under-reported to the Indian Registry. This linkage enabled MCHP to provide a more accurate picture of First Nations health status and use of health care services than otherwise would have been available. Ongoing linkages with Manitoba Health data, as well as similar linkages elsewhere in Canada, are encouraged.