Does Tall Man lettering prevent drug name confusion errors? Incomplete and conflicting evidence suggest need for definitive study.

To cite: Lambert BL, Schroeder SR, Galanter WL. BMJ Qual Saf 2016;25: 213–217. Wrong-drug errors, thought to be caused primarily by drug names that look and/or sound alike, occur at a rate of about one error per thousand dispensed prescriptions in the outpatient setting and one per thousand orders in the inpatient setting. 2 Most are relatively benign, but some cause severe or even fatal harm. One of the best known attempts to reduce drug name confusion has been the use of mixed case or ‘Tall Man’ lettering. The idea is to use capital letters to maximise the visual perceptual difference between two similar drug names. Thus, vinblastine and vincristine become vinBLAStine and vinCRIStine. If some look-alike/soundalike (LASA) mix-ups are caused by errors in visual perception, the reasoning goes, then making the names more visually distinct should reduce the probability of confusion and error. After being endorsed by the US Food and Drug Administration (FDA), the Institute for Safe Medication Practices (ISMP), The Joint Commission and others, the practice has become widespread. However, apart from limited evidence of effectiveness in laboratory settings, no evidence shows that this technique prevents drug name confusion errors in clinical practice. Zhong et al attempted to assess the effect of Tall Man lettering on drug name confusion errors in a large scale, longitudinal, observational study. They conclude that this widely disseminated error-prevention strategy had no measurable effect on the rate of drug name confusions in 9 years of data from 42 children’s hospitals in the USA. Below we comment on methodological issues in the Zhong et al study, review laboratory research on Tall Man lettering and consider policy implications. METHODOLOGICAL ISSUES The authors are to be commended for conducting a large-scale, empirical test of the effect of Tall Man lettering on the drug name confusion error rate in realworld clinical settings. The paper has many strengths, including its use of an interrupted time series design to test the main hypothesis. The scale of the paper is impressive, covering 1.6 million orders from 42 hospitals over 9 years (2004– 2012). Still, there are limitations to be noted, beyond those raised by the authors. The most significant limitation is that it is unknown at what point each of the 42 study hospitals implemented Tall Man (if at all), and for which pairs of names. These sites likely began the study period with paper-based ordering and moved to computerised provider order entry (CPOE), though some may have been using CPOE prior to 2004. Both the availability of Tall Man capability and the specific pairs selected for Tall Man treatment would have been decided by the hospital, the electronic medical record vendor or the medication knowledge base vendor. It is possible that none or not all of the 11 pairs of names studied by Zhong et al were converted to Tall Man at every site, and some pairs may have been converted earlier than 2007. The authors did not document whether Tall Man was actually in use in the 42 study hospitals, nor did they confirm whether or at what point the each of the 11 pairs of names selected for analysis was subject to Tall Man treatment in each hospital. Although recommended by the 2007 report of The Joint Commission as a national patient safety goal, Tall Man was never required by any regulatory body. It was one of several safe practices hospitals Editor’s choice Scan to access more free content EDITORIAL