Objectives To improve patient safety, we investigated near-miss dispensing errors in our hospital and evaluated the effectiveness of specific preventive strategies.

Methods The incidence and type of near-miss dispensing errors in a single hospital in Taiwan were identified in 2013. The causes of dispensing errors were analysed by consensus of an expert panel comprising a senior pharmacist on duty, a group leader in the pharmacy and an author. Because alphabetical trade names were routinely used in our pharmacy, they were used for similarity analysis. Trigram-2b and normalised edit distance (NED) were used to calculate orthographic similarity and distance measure, respectively. The correlation between drug-name confusion and dispensing errors was then studied. Preventive strategies, including the introduction of tall man letters, were completed at the end of 2013, and error data were then recollected in 2014. Differences between before and after the interventions were examined by t-test.

Results Before the intervention, look-alike alphabetical names were the main cause of dispensing wrong medicine (134/202, 66.3%). The frequency of near-miss dispensing errors correlated significantly with drug-name similarity (p<0.01). After implementation of preventive strategies, dispensing errors due to drug-name confusion were reduced significantly (77/140, 55.0%, p=0.004).

Conclusions The frequency of near-miss drug dispensing errors correlated with greater similarity or lower NED scores, and dispensing errors related to drug-name confusion were significantly reduced by our interventions. However, other dispensing errors might need to be investigated in order to prevent them.