Frequency of and risk factors for medication errors by pharmacists during order verification in a tertiary care medical center.

PURPOSE: The frequency of and risk factors for medication errors by pharmacists during order verification in a tertiary care medical center were reviewed. METHODS: This retrospective, secondary database study was conducted at a large tertiary care medical center in Houston, Texas. Inpatient and outpatient medication orders and medication errors recorded between July 1, 2011, and June 30, 2012, were reviewed. Independent variables assessed as risk factors for medication errors included workload (mean number of orders verified per pharmacist per shift), work environment (type of day, type of shift, and mean number of pharmacists per shift), and nonmodifiable characteristics of the pharmacist (type of pharmacy degree obtained, age, number of years practicing, and number of years at the institution). RESULTS: A total of 1,887,751 medication orders, 92 medication error events, and 50 pharmacists were included in the study. The overall error rate was 4.87 errors per 100,000 verified orders. An increasing medication error rate was associated with an increased number of orders verified per pharmacist (p = 0.007), the type of shift (p = 0.021), the type of day (p = 0.002), and the mean number of pharmacists per shift (p = 0.001). Pharmacist demographic variables were not associated with risk of error. The number of orders per shift was identified as a significant independent risk factor for medication errors (p = 0.019). CONCLUSION: An increase in the number of orders verified per shift was associated with an increased rate of pharmacist errors during order verification in a tertiary care medical center.