User:Brucelambert/sandbox/Drug Name Confusion

A medication error is a type of medical error involving drugs. A drug name confusion is a type of medication error that occurs when two drug names that look or sound alike are confused with one another. Drug name confusions are a sub-type of wrong drug errors. A wrong drug error occurs whenever a patient receives a drug other than the one that was intended. Drug name confusions are a common cause of wrong drug errors, but there are other causes, such as menu-selection errors or similarities in labeling, packaging, or storage location. Drug name confusions can and do occur any stage of the drug use process: prescribing, transcribing, dispensing, administration, and monitoring.

The U.S. Food and Drug Administration and the Institute for Safe Medication Practices have published lists of drug names that have been confused or may be vulnerable to confusion.

Drug Names

The system for naming drugs is complex and sometimes confusing, with each drug typically having at least three distinct names: a brand name (e.g., Tylenol), a generic or non-proprietary name (e.g., acetaminophen), and a chemical name (e.g., N-acetyl-p-aminophenol). Drug names can and do differ across national boundaries (although not always). Even within one country, it is difficult to say precisely how many drug names exist or what the definitive list of names is. Within countries, the regulatory agency in charge of medicines typically maintains a list of drug products approved for human and veterinary use, but these lists are not completely exhaustive, often lacking so-called house brand names, common names, abbreviations, and other unofficial variant names. In the United States, the Electronic Orange Book data files contain listings on all drug approved for use. Alternatively, the RxNorm project also contains data on the majority of drug products used in the U.S.

Causes

Drug name confusions are thought to be caused by errors in visual perception, auditory perception, short-term memory, and motor control. Two factors that drive these errors are similarity and familiarity. Similarity in spelling or pronunciation influences which names will be confused, with the probability of two names being confused generally increasing as similarity increases. Similarity between two drug names can be measured objectively, using any of a number of string similarity measures such as edit distance.

Whereas similarity influences which pairs of names are likely to be confused (e.g., hydroxyzine and hydralazine), familiarity tends to influence probability and the direction of the confusion (i.e., which name is substituted for which). Perceptual accuracy increases as familiarity increases.

Figure 1. Auditory perception accuracy as a function of familiarity. For each level of familiarity, the dark bar represents the percent of incorrect responses as a percent of the total number of responses for that participant group. The light bar represents the percent of correct responses at that familiarity level. The line represents the percent correct at a given level of familiarity.

Familarity influences the direction of an error (e.g., is Drug A heard when Drug B is presented, or vice versa). Generally, a more familiar name will be mistakenly heard when a less familiar name is presented. Errors in the other direction (from more familiar to less familiar) are much less common.

Direction of substitution errors as a function of difference in log prescribing frequency. The bar chart is a histogram of frequency differences between stimulus names and substituted names. The bottom part of each vertical column represents the number of times the substituted name was less frequently prescribed than the stimulus name (left axis). The top portion represents the number of times the substituted name was more frequently prescribed than the stimulus name. The line represents the percent of substitution errors wherein the substituted name was more frequently prescribed than the stimulus name (right axis). The graphs show that when one name is mistaken for another, the substituted name is almost always more frequently prescribed than the name which was misheard. The probability of error is not a symmetrical function of similarity. Relatively low frequency names are liable to be misheard as their higher frequency neighbors, but not vice versa.

Familiarity is the underlying psychological phenomenon, but it is not typically measured directly. Prescribing frequency is often used as a proxy for familiarity, with more frequently prescribed names assumed to be more familiar.

Incidence

The precise incidence of drug name confusions is not known because the overwhelming majority of medication errors are not reported or collected in a central repository. The most reliable information available about the rate of wrong drug errors and drug name confusions comes from observational studies of inpatient and outpatient pharmacy systems.

References

https://en.wikipedia.org/wiki/Tall_Man_lettering

External links

• ISMP's List of Confused Drug Names
• Look-Alike, Sound-Alike Medication Names
• Name Differentiation Project
• Medication Errors
• List of Confused Drug Names
• Preventing Medication Errors: Quality Chasm Series