Efforts to improve medication safety focus on preventing potential adverse drug events (ADEs, medication errors with a high likelihood of resulting in patient harm), under the assumption that preventing these near misses will reduce medication-related harm. However, the proportion of potential ADEs that result in actual preventable ADEs is controversial. This analysis of data from a prior study of medication administration errors found that 7.5% of potential ADEs resulted in actual clinical harm for patients. The authors point out that this apparently low incidence of preventable ADEs would still result in more than 4000 preventable ADEs every year at a 700-bed hospital.