Medication Error Events In Ontario Acute Care Hospitals

Background and Objective: In 2002, the Institute for Safe Medication Practices Canada (ISMP Canada) collaborated with several hospitals to determine the feasibility of using an electronic system to document and report medication error events and assess medication-use processes. This article provides an overview of the events reported and makes limited comparisons with similar data from US studies.Methods: A standard electronic submission system for documenting medication error events was made available to 14 acute care hospitals in Ontario. The hospitals collected data on medication error events identified by usual criteria and procedures over a 12-month period and submitted the data to ISMP Canada electronically. Analysis of the data focused on the frequency of errors by severity of consequence to the patient, type of outcome, therapeutic class of drugs involved, stage of the medication-use process at which the error occurred, types of error, and hospital-identified cause(s). Parallel analyses were undertaken for the subsets of reported errors classified as adverse drug events (ADEs) and potential ADEs.Results: The 4243 errors examined represent 0.86 errors per bed and 0.25 errors per 1000 doses of medication dispensed. Only 120 (2.8%) of the errors resulted in or possibly contributed to patient harm and were classified as ADEs. No error resulted in death. The 685 errors (16.1%) that reached patients and for which monitoring or intervention were required, but that were not implicated in patient harm, were classified as potential ADEs. The most commonly involved drug classes were central nervous system agents (including analgesics, sedatives, and antipsychotic drugs) (25.6%), blood formation and coagulation agents (12.7%), anti-infective drugs (12.3%), cardiovascular drugs ((12.0%), and hormones and synthetic substitutes (9.9%). The most frequently involved individual drugs were insulin, warfarin, heparin, morphine, furosemide, potassium chloride, epoetin, electrolyte solutions, and cefazolin. Errors occurred most frequently in the medication administration process (56.6%) and the order entry and transcription stages (32.6%) of the drug-use process. Contributing factors most frequently identified included miscommunication of a drug order; environmental, staffing or workload problems; lack of staff education; and lack of quality control or independent check systems.Conclusions: The participating hospitals were willing to submit medication error reports electronically, and compilation of the resulting data provided a snapshot of medication error events detected and documented using usual practices. A very small proportion of the events resulted in harm to patients, but a larger proportion had the potential to cause harm, and patient monitoring or intervention was required to prevent injury. Strategies for reducing the incidence of medication errors must recognize the contribution of both human and system factors to error events.