More orders per shift linked to medication errors, says AJHP study

More than 400 orders associated with highest risk of errors

The demanding workload on pharmacists is a reality many know too well. Now a new study links the amount of orders verified by health-system pharmacists to the frequency of medication errors.

The study, published in the American Journal of Health-System Pharmacy (AJHP), found that 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.

“The primary finding from this study was that the number of medication errors increased with the number of orders verified per pharmacist per shift,” wrote the study authors. According to the findings, the verification of more than 400 orders per shift per pharmacist was associated with the highest risk of errors.

“Once we got to the 400 mark, meaning 400 orders verified per pharmacist, [we] started to reach a higher number of errors,” said Christy Gorbach, PharmD, coauthor of the study and Pharmacy Shift Coordinator at Houston Methodist Hospital, during an interview on the podcast AJHP Voices about the study. She said this number could be useful information for other institutions to consider when benchmarking its operations.

Unique study focus

Researchers from the Houston Methodist Hospital and the University of Houston College of Pharmacy in Houston, analyzed 1,887,751 inpatient and outpatient medication orders and 92 medication error events recorded between July 2011 and June 2012 at a tertiary care medical center in Houston that operates roughly 1,000 beds.

The overall error rate was 4.87 errors per 100,000 verified orders, according to the results.

A medication error was defined by pharmacist-related error-event reports collected from the study institution through a voluntary error reporting system—where personnel are not penalized for reporting errors but actually incentivized to do so. They homed in on orders that were reported only from nonpharmacist personnel in order to help mitigate the risk of bias.

While the topic of medication errors by pharmacists has been studied extensively, Kevin Garey, PharmD, Professor and Chair of the University of Houston College of Pharmacy, told Pharmacy Today that very few studies have looked at the reasons why medication errors occur during the order verification process.

The order verification process is a very high-volume event for health-system pharmacists, with millions of prescriptions verified per year. In a typical process, a provider enters an order, it comes to the pharmacy through an electronic system, the pharmacist verifies it electronically, and then it goes through the Medication Administration Record before the nurse administers the medication. 

Additional factors

In addition to workload, researchers also wanted to assess how work environment and pharmacist characteristics might increase the likelihood of a pharmacist committing an error during medication order verification.

They found that errors occurred more often during the evening shift (10.57 per 100 shifts), followed by the day shift (7.33 errors per 100 shifts), and the night shift (4.55 errors per 100 shifts). The report also found that significantly more errors occurred during weekdays versus weekends.

The research team considered pharmacist age, type of pharmacy degree, number of years at the site, and number of years practicing as a pharmacist, but found no statistical significance correlating these characteristics with medication errors.

Study authors indicated that new employees receive extensive training, and the fact that younger employees did not have a higher error rate than their older coworkers may indicate value in that training. However, this possibility would require validation in future studies, they wrote.

While no specific medication class was identified with a higher rate of error, researchers said that the five medications most commonly associated with an error event were: pneumococcal vaccine (13%) for duplicate order, piperacillin–tazobactam 3.375-g vial (4%) for allergy or wrong dose, influenza virus vaccine (3%) for duplicate order, warfarin sodium 5-mg tablet (2%) for wrong dose, and dexamethasone injection 4 mg/mL (2%) for wrong dose.

The most common error types reported were wrong dose or wrong drug or substance.

The researchers said that additional studies are needed to validate this finding and to identify a maximum number of orders verified per hour that maintains safe practices as it relates to other hospital pharmacy practice settings.