Background Prescribing errors are common. It has been suggested that the severity as well as the frequency of errors should be assessed when measuring prescribing error rates. This would provide more clinically relevant information, and allow more complete evaluation of the effectiveness of interventions designed to reduce errors. Objective The objective of this systematic review was to describe the tools used to assess prescribing error severity in studies reporting hospital prescribing error rates. Data Sources The following databases were searched: MEDLINE, EMBASE, International Pharmaceutical Abstracts, and CINAHL (January 1985-January 2013). Study Selection We included studies that reported the detection and rate of prescribing errors in prescriptions for adult and/or pediatric hospital inpatients, or elaborated on the properties of severity assessment tools used by these studies. Studies not published in English, or that evaluated errors for only one disease or drug class, one route of administration, or one type of prescribing error, were excluded, as were letters and conference abstracts. One reviewer screened all abstracts and obtained complete articles. A second reviewer assessed 10 % of all abstracts and complete articles to check reliability of the screening process. Appraisal Tools were appraised for country and method of development, whether the tool assessed actual or potential harm, levels of severity assessed, and results of any validity and reliability studies. Results Fifty-seven percent of 107 studies measuring prescribing error rates included an assessment of severity. Forty tools were identified that assessed severity, only two of which had acceptable reliability and validity. In general, little information was given on the method of development or ease of use of the tools, although one tool required four reviewers and was thus potentially time consuming. Limitations The review was limited to studies written in English. One of the review authors was also the author of one of the tools, giving a potential source of bias. Conclusion A wide range of severity assessment tools are used in the literature. Developing a basis of comparison between tools would potentially be helpful in comparing findings across studies. There is a potential need to establish a less time-consuming method of measuring severity of prescribing error, with acceptable international reliability and validity. BackgroundPrescribing errors are common in hospital inpatients. While errors are under-reported in clinical practice, research studies using methods other than spontaneous reporting have found much higher rates. In a recent systematic review of the prevalence, incidence, and nature of prescribing errors in hospital inpatients (including a wider range of methods for identifying errors), the median error rates in 65 eligible studies were 7 % of medication orders, Electronic supplementary material The online version of this article

Page 1153, column 2, section 3.3, paragraph 1, lines 1-5: The following two sentences, which previously read:''Thirty (75 %) tools were based on potential rather than actual harm. It is of interest that the NCC MERP index [68] was developed to assess actual harm but was subsequently used or adapted to assess potential harm in six studies [48, 50, 51,[54][55][56].'' should read:''Twenty nine (72.5 %) were based on potential rather than actual harm. It is of interest that the NCC MERP index [68] was developed to assess actual harm but was subsequently used or adapted to assess potential harm in five studies [50][51][54][55][56].'' Page 1155, column 1, section 3.6, paragraph 1, lines 7-11: The following sentence, which previously read:''Forrey et al. [48] found that the original NCC MERP index [68] had 74 % alignment and that their adapted version had 81.0-83.9 % alignment when potential harm assessment was compared with actual harm.'' should read: ''Forrey et al. [48] found that the original NCC MERP index [68] had 74 % alignment and that their adapted version had 81.0-83.9 % alignment when the severity scores of an expert panel (used as a gold standard) were compared with those of individual raters.''The online version of the original article can be found under