title: Observational Studies of Drug Safety in Multi-Database Studies: Methodological Challenges and Opportunities.
abstract: OBJECTIVE
  The Canadian Network for Observational Drug Effect Studies (CNODES), a network of researchers and databases, is a collaborating center of the Drug Safety and Effectiveness Network. CNODES' main mandate is to conduct observational studies of drug safety based on queries developed and submitted by Health Canada and other federal, provincial, and territorial stakeholders. Through a case study we explore several methodological opportunities and challenges that arise in distributed pharmacoepidemiology networks.
  
  
  METHODS
  We use as a case study a study of proton pump inhibitors and hospitalization for community-acquired pneumonia. Challenges arise in the design and conduct of studies at individual sites, and then with processes and methods for combining data. On the other hand, distributed networks provide opportunities, such as the ability to detect and understand heterogeneity, in sample sizes that would typically be impossible for a single study.
  
  
  CONCLUSIONS
  Networks such as CNODES provide the opportunity to detect and quantify important safety signals from administrative data, and provide many challenges for methods research in pharmacoepidemiology using distributed data. As networks increase in size and scope of research questions, the need for methodological developments should continue to grow.
authors.affiliation: McGill University.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Platt
authors.affiliation: University of British Columbia.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Dormuth
authors.affiliation: University of Manitoba.
authors.forename: Dan
authors.initials: D
authors.lastname: Chateau
authors.affiliation: McGill University.
authors.forename: Kristian
authors.initials: K
authors.lastname: Filion
keywords: Data analysis method; Methods; Research networks