Medication error research typically focuses on just one stage of the medication use process: prescribing, transcribing, dispensing, administration or monitoring. Such simplification is required so that manageable boundaries can be set around the research, and to make it easier to specify error definitions, methods and denominators. However, this is clearly very simplistic, and from the patient's perspective it is a somewhat arbitrary and meaningless distinction. In addition, many quantitative studies present the numbers of doses, drugs or patients with one or more errors, which makes it easy to miss the fact that multiple errors can occur together. While studies of adverse drug events (ADEs) typically include a wider range of sources of harm, some analyses include only the first ADE identified for each patient. Collectively, this means we may miss the opportunity to explore how multiple errors may occur together in the same patient. And yet detailed investigations into catastrophic medication errors typically reveal a whole concatenation of errors and failed defences, involving multiple stages of the medication use process.1 ,2

We therefore need to better understand how errors are related across the whole medication process. A paper presented by Carayon et al3 explores this very issue in two US adult critical care units, shedding new light on the complexities surrounding medication use in the hospital setting. While the critical care setting is likely to be particularly complex, with patients prescribed high numbers of medications, particularly intravenously, the principles are likely to apply much more widely.

Carayon et al took the novel approach of analysing errors both by group (where more than one error occurs for the same medication order at the same …