Longitudinal Immigration Database (IMDB) linked to the Discharge Abstract Database (DAD)

The purpose of this linkage project was to create a linked dataset that would enable researchers to better understand immigrants' use of hospital care services, and fill a key data gap to allow for a greater understanding of differences that may exist among immigrants in Canada who are otherwise not identified in the administrative data.

To accomplish this, the Longitudinal Immigration Database (IMDB) was linked to hospital discharge events obtained from the Discharge Abstract Database (DAD) for all provinces and territories (excluding Quebec). Information for immigrants landing in Canada between 1980 and 2013 were obtained from the IMDB, and these were linked to hospitalization records for fiscal years 2000/01 through 2013/14.

Longitudinal Immigration Database (IMDB)

The IMDB is an administrative census of immigrants who had landed in Canada since 1980. The IMDB combines an administrative Immigrant Landing File (ILF) and a Non-Permanent Resident Permit File (NRF-Permit) with the T1 Family File (T1FF) through exact matching record linkage techniques. It includes one file for each tax year since 1982, two files containing immigration characteristics at the person al level and one permit file for non-permanent residents. It should be noted that the version of the IMDB that was linked for the current study (i.e., the 2013 IMDB), did not include non-permanent residents. A linkage cohort file containing the identifiers of the IMDB immigrants who were eligible for linkage to the DAD is available through the RDC to enable researchers to verify membership of the IMDB linkage cohort. For information about the analytical variables included in the IMDB, researchers should consult the IMDB documentation available from your RDC analyst.

Discharge Abstract Database (DAD)

The Discharge Abstract Database (DAD) captures administrative, clinical and demographic information on hospital discharges (including in-hospital deaths, sign-outs and transfers) from all provinces and territories ^{Footnote 1}, except Quebec. Over time, the DAD has also been used to capture data on day surgery procedures, long-term care, rehabilitation and other types of care. Hospitals in Manitoba started submitting their records to DAD from April 1, 2004. Throughout the fiscal years that are covered in the linkage, there were openings, closure and mergers of institutions.

In the DAD, jurisdiction-specific instructions for collection of data elements evolve over time. Collection of each data element may be mandatory, mandatory if applicable, optional or not applicable. Collection requirements can vary by jurisdiction and by data year.

Researchers will find the listings of DAD data elements under the heading "Data Elements" at the DAD Metadata website. Please note that not all DAD data elements are included in the RDC DAD datasets for this linkage project. A list of available DAD variables is contained in user guide for the linked dataset. The documents on the website include information on mandatory versus optional collection status for each data element by jurisdiction, which is key to understanding coverage of data elements in the DAD.

For this record linkage, DAD records that linked to IMDB cohort members from fiscal years 2000/01 through 2013/2014 were included.

File structure, layout

All variables from the IMDB are available for analysis. Please see appropriate data dictionaries, available from your RDC analyst.

The DAD is an event based file, meaning that there will be more than one record for a person who was hospitalized more than once in the same fiscal year. During the linkage process, all DAD records belonging to the same IMDB cohort member were identified using their IMDB_ID. Researchers can then choose to use the DAD file as an event based file (each row of data represents a hospitalization) or a person based file (each row of data represents an individual).

In order to use the file as a person based file, the researcher must transform the data to include all hospital information for one person as one record (one row on the data file).