In its 1999 landmark paper, "To Err is Human," the U.S. Institute of Medicine stressed the fact that medication errors are the eighth most frequent cause of death in the United States, more frequent than car accidents, breast cancer, or AIDS [¹]. Adverse drug events, defined as injury caused by medical management involving drugs, are the most prevalent cause of inpatient injury and are often found to be preventable [^2-5].

Dormann et al. reported adverse drug events (ADEs) to be the reason for 6% of hospital admissions in internal medicine in Germany, causing additional health care expenditures of several hundred million Euros. Almost half of the ADEs observed in that study were considered preventable [⁶]. Buajourdet et al. revealed an incidence of 18% fatal adverse drug events among inpatients who died in the Department for Internal Medicine in Norway [⁷]. A comprehensive study in the United States showed that almost every fifth medication dose reaching the patient is incorrect [⁸].

The drug prescription and administration process in most hospitals worldwide is still based on handwritten medical chart entries [²,⁹,¹⁰]. Several steps in this complex and unchecked process can harbour a high number of relevant errors. These undetected medication errors in patients' drug documentation may be a significant source of ADEs [¹¹,¹²].

This study was performed to identify and quantify possible sources of error in the handwritten prescription and medication process in a large Swiss university hospital. Medical records were analyzed for readability of handwritten medication entries and for errors in the medication documentation. Possible strategies to reduce the incidence of errors in this high-risk process are discussed [¹³].

This study revealed a high error rate in the prescription process in a large Swiss University Hospital. The process of transcribing a drug order manually from one sheet to another appears to be a significant source of error. More than half of the handwritten prescriptions were rated as poorly readable or unreadable.

It is well known that errors in the medication process can lead to adverse drug events [⁴,⁸,¹¹,¹⁶,¹⁷]. Negligence and omission have been reported to be a prominent source of error, and transcription errors can potentially compromise patient outcomes [³,⁴,⁸,¹¹,¹⁸]. In our study, at least one error in the prescription-transcription process was found in 3.5% of all prescribed agents. This was similar to the results published by Bobb in 2004 (6.2%) and Bates in 1995 (5.3%), whereas Barker found a markedly higher error rate of 19% [²,⁸,¹⁶]. Most errors found in our study were related to the transcription of prescriptions (53.3%). Others have reported lower transcription error rates (Bobb 2004: 4.9%; Leape 1995: 11.9%; Barker 2002, for omitted drug orders: 30.2%) [²,⁸,¹¹]. These differences are mainly due to diverse definitions of error types and methodological approaches chosen by investigators based on the particular documentation practices in their health care system. Moreover, unlike other investigations, our study focussed on the handwritten medication documentation and its error proneness.

Compared to the data from Winslow et al. (20% illegible or readable with effort) and Aylamani et al., our study revealed an even worse legibility of the handwriting of physicians [¹⁹,²⁰]. Agreement among the three raters in the readability evaluation was low, thus making evident that there are not only considerable differences in the quality of handwriting between different physicians but also between the subjective ability to read different handwritings. In addition, even when the two physicians rated the same prescriptions on two occasions, the agreement was not excellent. These findings are consistent with those from Alyamani et al., who also reported considerably low levels of illegibility (0.5%) in a consensus group of physicians. Interestingly, higher rates were found in the same study if the analysis was performed by nursing staff (2.5%) [²⁰].

Different solutions to avoid errors in the handwritten prescription process are available. Omitting transcribing by having physicians write the prescriptions directly on medication lists removes one important source of errors. However, this does not solve the fundamental problem of poor readability of handwriting. Therefore, Computerized Physician Order Entry (CPOE) software solutions are increasingly taken into service and prove to eliminate multiple sources of error. In addition to the replacement of handwritten prescriptions by easily readable digital fonts, and the factual elimination of documentation errors, these software programs feature various security functions, such as checking for drug interactions, dosage levels, laboratory findings, and contraindications [²,¹³,^21-23]. Of course, the use of CPOE systems cannot prevent every documentation error; it may even introduce new sources of error. For example, insufficient training of staff as well as poor quality of soft- and/or hardware have shown to facilitate additional error risks [¹⁰]. However, most of the data published supports the claim that CPOE systems provide a valuable solution for improving the quality of the medication process in hospitals [⁹,^24-26].

This study has some limitations. It is a retrospective evaluation and, therefore, discussions between doctors and nurses concerning patient medication could not be measured. However, an unblinded prospective approach may lead to exceptionally careful staff behavior and over-accurate medication documentation as a result of being supervised. According to Alyamani et al., the level of illegibility identified by nurses may be higher compared to the analysis of a consensus group [²⁰]. Hence, the level of illegibility found may have differed if a nurse had participated in the investigators group. This study was conducted on one ward in a single institution, limiting the generalizability of the findings presented in this paper. Further studies should involve non-surgical departments that treat patients with complex medical conditions requiring multiple drugs and long hospital stays.

In conclusion, this study found a high error rate in the medication process in a university hospital. Replacing the traditional handwritten documentation process with information technology may potentially improve the quality of the medication process.

None of the authors report having competing interests that could inappropriately influence the content of this work.

MJH was involved in the conception of the paper, literature review, manuscript preparation, editing and submission. LPS performed the statistical analyses and contributed to the conception and editing of the paper. CR was involved in the manuscript preparation and editing of the paper. SE conceived the idea of the study. All authors contributed to the editing and review of the manuscript and gave their approval of the final manuscript.

The pre-publication history for this paper can be accessed here:

http://www.biomedcentral.com/1472-6963/11/199/prepub

We would like to thank Agnes Zelinka, M.D, Kathrin Aeschlimann, Ulrich Haupt, M.D, Brigitte Liebi, Regula Wenger and Nikola Jejina, M.Sc. for their kind assistance and contributions.

Supported a by a grant from CTI Life Sciences, Federal Office for Professional Education and Technology OPET, Switzerland. CTI had no influence on data collection or interpretation, or on the content of the manuscript.