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The Ontario Cancer Data Linkage Project (‘cd-link’) is an initiative of the Ontario Institute for Cancer Research/Cancer Care Ontario Health Services Research Program. Through a collaborative agreement between the Institute for Clinical Evaluative Sciences (ICES) and Cancer Care Ontario (CCO), cd-link is a data release program whereby administrative datasets relevant to cancer health services research, such as the Ontario Cancer Registry and Ontario Health Insurance Plan claims are linked, de-identified and with the protections of a comprehensive Data Use Agreement, provided directly to researchers.

How are the data de-identified?

An innovation of the cd-link initiative is the mechanism by which the data are de-identified. All data are made anonymous by removing personal identifiers, according to Ontario (PHIPA) and U.S. (HIPAA) privacy legislation.

To achieve this, identifiers are removed or scrambled, and all dates more specific than year are converted to the number of days relative to the index date (e.g., diagnosis date). Data sets are then evaluated with the Privacy Analytics Risk Assessment Tool, a program that measures and manages the re-identification risk of each data release. All data releases must have a re-identification risk of ≤ 0.33 (at least three similar observations in the data sets released) and preferably at least ≤ 0.20 (at least five similar observations in the datasets released). Consequently, variables may be modified to ensure that each data release meets these criteria. For example, age at index may be grouped into five-year bands, or geographic regions may be combined.

The de-identification process is conducted by a cd-link analyst in collaboration with the researcher to ensure that the final de-identified data still allow the researcher to achieve the objectives of his/her research.

Am I eligible and how much does it cost?

The program is currently available only to researchers at Ontario academic institutions. Currently, there is no charge for filling data requests and providing access to the principal investigator and analyst. Additional users can be given access for a cost of $300 each. At this time, applications funded by for-profit interests will not be considered.

How do I apply?

Researchers must prepare a study proposal (approximately five pages) consisting of the required elements listed below. Failure to include all required elements will delay the review and approval process:

  • Rationale and objectives
  • Data sources and variables requested, including justification for each variable
  • Planned analyses and planned use of the data
  • Expected products
  • Funding sources
  • Study timeline
  • List of research staff members, their role and contact information (include postal address, e-mail address and telephone number).

Principal investigators must submit their proposals electronically to the Health Services Research (HSR) Program Leader, Dr. Craig Earle, for preliminary review. Dr. Earle will determine feasibility of the study and appropriate use of the data requested at the time.

What datasets are available?

  • CIHI Discharge Abstract Database (CIHI-DAD)
  • CIHI National Ambulatory Care Reporting System (NACRS)
  • Continuing Care Reporting System (CCRS)
  • Home Care Database (HCD) / Ontario Home Care Administrative System (OHCAS)
  • New Drug Funding Program (NDFP)
  • National Rehabilitation Reporting System (NRS)
  • Ontario Breast Screening Program (OBSP)
  • Ontario Cancer Registry (OCR)
  • Ontario Drug Benefit Claims (ODB)
  • Ontario Health Insurance Plan Claims Database (OHIP)
  • Registered Persons Database (RPDB)

See the ICES Data Dictionary, a detailed description of the ICES Data Repository.

Typically, an incident or decedent cohort is created based on the Ontario Cancer Registry, and data from additional sources pertaining to the cohort is also included. Optionally, a 5% sample of the general population and its attendant data are also included. Please note: While the general population sample is subject to the same age/sex exclusion criteria as the case cohort, it is not a matched set (i.e., the age-sex distribution may differ markedly between the cases and the controls).

For more information please contact:

Submission enquiries:

Craig Earle, Program Leader
Health Services Research Program
Ontario Institute for Cancer Research and Cancer Care Ontario