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Privacy concerns hinder medical registry studies necessary to improve patient care


Development of a representative national consent-based registry, designed to monitor and improve stroke care, demonstrates the practical difficulty of obtaining informed consent for medical registry research, says a new study from the Institute for Clinical Evaluative Sciences (ICES) and the Canadian Stroke Network appearing in the current issue of the New England Journal of Medicine (NEJM).

Researchers examined the effectiveness of a comprehensive attempt to obtain informed consent from stroke patients participating in the Registry of the Canadian Stroke Network (RCSN), a registry comprised of 20 hospital stroke centres across eight Canadian provinces set up to monitor and improve stroke care in Canada. The study tracked the overall participation rate (i.e. the consent rate among all potential stroke patients at each stroke centre) and characteristics of consenting patients between June 2001 and December 2002. The registry was designed to capture information on the in-hospital course of each stroke patient, along with a follow-up patient interview, but did not involve the testing of any new interventions.


  • During phase 1 of the project (June 2001 to Feb. 2002) the overall participation rate was 39% of 4,285 eligible patients. This rose to only 51% of 2,823 eligible patients for phase 2 (June 2002 to Dec. 2002). An ideal registry would have a participation rate of 95 to 100%.
  • Barriers to obtaining consent included patients who died or left hospital before they could be approached for consent, patients who were not admitted to hospital, patients who were cognitively impaired and had no surrogate decision maker, and patients who could not speak English or French. Approximately 5 out of 6 patients who could be approached agreed to participate while 1 out of 6 declined. Obtaining patient consent took an average of 40 minutes and two bedside visits for each patient.
  • The difficulties in obtaining consent resulted in major biases for patients included in the registry. For example, the in-hospital mortality rate was 7% among patients enrolled in the registry vs. 22% for patients who were not enrolled. Patients who were enrolled were younger and healthier than patients who were not. Data from patients in the registry cannot be used to identify why stroke patients have such high mortality rates because many deceased patients could not be enrolled in the registry.
  • A quarter of the registry’s budget was spent on consent-related issues.

“Patients who use the healthcare system in Canada and other countries have benefited tremendously from medical knowledge gained from observational clinical registry studies that have not obtained patient consent, but which have used appropriate safeguards to protect patient confidentiality,” said lead author, ICES senior scientist, and Canada Research Chair in Health Services Research, Dr. Jack Tu.

“For instance, there are cancer registries which allow us to determine if there are communities with higher than expected cancer rates, and cardiac surgery waiting list registries which allow us to identify patients at high risk of dying on the waiting list so that they are treated first. These types of research studies are only possible because they include all patients who are being treated for a given condition.

“However, in recent years, increasing concerns about the privacy of personal health information has led to the development of privacy legislation and policies in some jurisdictions that require researchers to obtain patient consent before any patient data can be entered into a registry and used for research purposes. While patient privacy is undoubtedly an important issue and needs to be safeguarded in these databases, the requirement for informed consent can lead to incomplete data, making the patients in these registries no longer representative of all patients with a given condition, and the registries of limited value for scientific studies.

“It can be practically very difficult to obtain patient consent from all patients to conduct these registry studies because of multiple barriers, such as those identified in the RCSN. It is important for the public to realize that the privacy risks to patients from these registries are very small because the data are usually anonymous (i.e., personal identifiers such as patient name and address are not included in the database), whereas the societal benefits can be quite substantial as many important medical studies aimed at improving patient care and public health are conducted using these databases.”

According to Dr. Tu, it is very important that researchers have the support of policy makers and research ethics boards to allow exemptions to the requirement for informed consent for medical registry research so that researchers can continue to conduct important clinical studies on topics such as disease surveillance, quality of care, and patient safety. “If we wish to continue to deliver the best possible medical care to patients, there needs to be a reasonable balance struck between the need to protect patient privacy and the need for improved health of the public through observational medical research studies,” he states. “We believe this can be achieved by allowing publicly-funded clinical registries to collect anonymous information on all types of patients with a given condition for the purposes of measuring and improving patient care and the healthcare system.”

“The Canadian Stroke Network is deeply committed to protecting patient privacy and confidentiality in our Registry,” says Dr. Antoine Hakim, CEO and scientific director of the Canadian Stroke Network. “But we also want to highlight the critical need for a stroke registry that includes all types of stroke patients to facilitate improvements in the quality of care provided to Canadian stroke patients.”

"This is a very important study that confirms my long-held view that a requirement to obtain informed consent may not be practical in all cases, such as the stroke registry, where there is a minimal risk to privacy, but much to be gained in terms of health benefits,” said Dr. Ann Cavoukian, information and privacy commissioner of Ontario. “In the context of our publicly funded healthcare system, I do not believe that the public interest is served by the rigid application of privacy rules to research using databases and registries without careful consideration of the costs, both in terms of resources and data quality. This study supports the policy direction in Ontario's proposed Health Information Protection Act that incorporates a flexible and balanced approach to the use and disclosure of personal health information for such purposes. I would encourage more research on the implications of informed consent in the context of health registries and research in general."

NEJM Editors Dr. Julie Ingelfinger and Dr. Jeffrey Drazen echo these comments in a corresponding editorial. The editorial cites the critical importance of clinical registries that allow physicians to learn from their successes and mistakes as key to medical progress. They state that “sadly, around the world, data repositories are now at risk of significant bias because concern about privacy has led to the requirement that consent be obtained before an individual person’s data can be included.” Dr. Ingelfinger and Dr. Drazen believe “the pendulum has swung too far” in the direction of protecting patient privacy and that “public health is threatened by incomplete data more than individual privacy is threatened by disease registries.”

The study, “Impracticability of informed consent in the Registry of the Canadian Stroke Network”, is in the April 1, 2004 issue of the New England Journal of Medicine (NEJM). The study was funded by an operating grant from the Canadian Stroke Network and the Ontario Ministry of Health and Long-Term Care.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners and practitioners to make decisions about care delivery and to develop policy.

The Canadian Stroke Network is one of 21 Networks of Centres of Excellence, the federal government’s flagship science and technology program. The Canadian Stroke Network is an independent, not-for-profit corporation established in 1999 to reduce the burden of stroke through leadership in research innovation. The Network is made up of more than 100 of the country’s best and brightest scientists, clinicians, rehabilitation specialists and knowledge-translation experts from 24 universities.


  • Julie Argles
  • Media Relations Officer, ICES
  • (416) 480-4055 ext. 3602 or cell (416) 432-8143
  • [email protected]


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