Introduction

In February 2004, two fatal medication errors occurred in the Calgary health region, Alberta, Canada, when two different dialysis patients received dialysate solution containing formulations. The story of patients dying unnecessarily in this way had a powerful effect on the public. Numerous (often sensationalistic) accounts in the lay media across the country speculated on possible causes of the errors, publicly chastised the pharmacy technicians and other professionals involved, and called into question the safety of all of Canada's healthcare institutions. As a result of these events, an independent inquiry of the incident was conducted, a new patient safety position was created for the region,1 a review of best practices was commissioned, and many changes were made to ensure “this would never happen again.” Often it is the public response to a story about an adverse event or medical error that drives changes in practice, rather than careful attention to the available evidence.2

Since the publication of the Institute of Medicine's report, To Err is Human: Building a Safer Health Care System,3 the safety of medications, and of patients in general, has caught the attention of the general public and hospital healthcare practitioners. This report identified medication errors as the single largest cause of medical errors in hospitals, accounting for some 7000 deaths each year in the United States. Another report estimated that more than one million medication errors occur every year in US hospitals,4 and about 5% of all admissions to hospital are related to adverse drug events.5 Since the report, most safety research has focused on measuring the incidence of adverse events, including medication errors, rather than evaluating the effectiveness of current or proposed safety practices relating to medication and patients. The use of potassium supplements and safe handling of potassium are examples …