Go to content

National network evaluating drug safety reports early results


Prescription medications remain one of the most common causes of severe adverse reactions in clinical medicine, accounting for an estimated 1,800 to 10,000 deaths annually in Canada. The need for drug safety research using an epidemiological approach has been clearly understood for decades, but such research has suffered from a lack of national coordination.

Today the Canadian Network for Observational Drug Effect Studies (CNODES) released its first report documenting progress towards its goal of creating a fully operational system for the rapid assessment of adverse drug effects in Canada.

The Institute for Clinical Evaluative Sciences (ICES) is the Ontario node of CNODES. Ontario is one of seven provinces involved in the network, which uses linked health data collected in each Canadian province to evaluate post-market drug safety and effectiveness. CNODES also uses data from the UK and the US and can perform analyses on a total population of more than 40 million people.

“The establishment of CNODES means we can rapidly respond to drug safety concerns in a fraction of the time that it took in the past. For example, investigations of the adverse effects of Vioxx on the heart (withdrawn from world markets in 2004) were conducted by separate teams of researchers using databases in Ontario, Quebec and Saskatchewan. The time taken to respond to the first report on safety concerns, published in November 2000, ranged from 3 to 9 years — an excessive period, considering the potential threat to public health posed by a widely used drug,” says Dr. David Henry, ICES CEO and lead of the CNODES database team.

The principles of operation of CNODES are:

  • Research questions come mainly from Health Canada or from provincial drug programs.
  • The linked health data used to estimate adverse effects stay within the provinces and are anonymous.
  • For each question, a study team formulates a detailed protocol enabling consistent analyses in each province.
  • Analyses are conducted “blind” to results obtained elsewhere to reduce bias.
  • Analyses are lodged centrally with a methods team that is responsible for combining the results to provide a summary estimate of the drug effect for the whole country.

Canada holds a rich resource in administrative health data, largely residing in provinces and territories. CNODES offers an opportunity to coordinate access to these data resources and use them to answer important questions about serious side effects of drugs in a timely fashion.

Studies performed in the first year of operation have examined the effects of cholesterol lowering drugs on the kidney, whether gastric acid inhibiting drugs increase the risk of pneumonia and whether drugs used to treat psychosis (e.g., schizophrenia) cause acute onset of diabetes.

“There are a number of important features of this unique collaboration,” says Dr. Samy Suissa, lead of the CNODES national network and a professor at McGill University in Montreal. “This is a distributed network, which means that the data analyses are first carried out at the provincial centres and are then combined to give Canadian estimates. The data remain in the provinces, where they belong. No provincial data will cross borders."

CNODES offers an opportunity to coordinate access to these data resources and use them to answer significant research questions for the health of Canadians.”CNODES is an academically-based distributed network of Canadian researchers and data centres with a commitment to rapid and sophisticated analysis of emerging drug safety signals in study populations totaling over 40 million people.

Authors: Samy Suissa, David Henry, Patricia Caetano, Colin R. Dormuth, Pierre Ernst, Brenda Hemmelgarn, Jacques LeLorier, Adrian Levy, Patricia J. Martens, J. Michael Paterson, Robert W. Platt, Ingrid Sketris and Gary Teare.

The study “CNODES: the Canadian Network for Observational Drug Effect Studies,” appears in the online journal Open Medicine.

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.


Read the Journal Article