Based on our study results, the adoption of ADCs effectively reduced medication errors in the ICU: the dispensing error rate reduced from 3.87 to 0 per 100,000 dispensations (p = .003), and the prescription error rate reduced from 3.03 to 1.75 per 100,000 prescriptions (p = .500) for all items. The administrative error rate decreased from 0.046–0.026% for the ADC items (p = .424). Our study also found that ADCs were effective in reducing errors that caused no harm (NCC MERP categories B–D).
Dispensing is a high-risk activity because of the heavy workload of pharmacists [14]. A dispensing error can be defined as the discrepancy between a prescription and a drug dispensation to a patient. A systematic review showed that most reported dispensing errors were near misses, meaning that they were detected before leaving the pharmacy; the dispensing error rates ranged from 0.015–33.5% [15]. Preventing dispensing errors reduces the risk of drug-related harm or death to patients. However, there are several preventive measures for traditional manual dispensing, but they are unlikely to fully eliminate mechanical errors because of the potential for human error [2]. The adoption of ADCs and other automated drug distribution systems is one of the major solutions for promoting medication safety, and they have attracted attention in several developed countries [16]. ADCs allow the physical separation of similar drugs, restrict drug access, and assist nurses in picking up medications through a guidance system [7]. A Swiss study comparing ADCs with traditional ward stocks found that ADCs can significantly reduce dispensing errors from 5–1% [17]. Another study conducted in Taiwan found that dispensing errors were reduced by 75% after the adoption of ADCs, even though ADCs were used to dispense prescriptions with only stat orders [5]. In the current study, we used ADCs for all prescriptions, including new, standing, and stat orders, which markedly reduced the risk of dispensing errors. Approximately 80% of the commonly used medicines were dispensed through the ADCs, and the error risk from human operation was reduced to one-fifth of the original for the remaining 20% of dispensations by pharmacists. The rate of dispensing errors dropped to zero after ADC adoption.
The primary function of the ADC is to ensure that drugs are dispensed and delivered correctly. Therefore, ADCs can prevent the administration of an incorrect dose or strength to the patient so far as they are supplied correctly [18]. However, once the drug was removed, administration accuracy depended on the nurse. The adoption of ADCs did not consistently reduce the medication errors of nurses. Fanning et al. reported that the use of ADCs in emergency rooms reduced medication selection and preparation errors [7]. Chapuis et al. also reported that setting up ADCs in the ICU could effectively reduce medication errors related to preparation and administration [6]. In contrast, some studies have shown that ADCs have no significant effects on administrative errors [19, 20]. In our study, the use of ADCs reduced the rate of administration of wrong doses but not the administrative errors. More than a quarter of the errors were due to the wrong time of administration (6 of 22, 27.3%). One possible reason for these errors is that the pick-up time for ADC items was too long. The remaining administrative errors after ADC adoption were errors that could not be prevented, such as administration to the wrong patients, administration of wrong drugs, or administration via the wrong routes. The number of unauthorized drug-related errors increased even after the introduction of ADCs. These errors were mainly related to inaccurate execution of the medication process or unfamiliarity with medications. Studies have demonstrated that sufficient medication knowledge can effectively prevent medication errors [7]. Therefore, improving relevant education and training for nursing may improve patient safety. Pharmacists should also participate in drug knowledge-related training to further reduce medication errors.
Drug prescription is the first step during the medication use process; however, only a few studies have investigated the impact of ADCs on prescription errors [21]. Because of the complexity of intensive care unit patients, studies have reported that pharmacist interventions have an important clinical impact in reducing prescription errors [22]. In our study, prescription errors were reduced from 3.03 to 1.75 per 100,000 prescriptions after the adoption of ADCs in intensive care units. Pharmacists had more time to spend on clinical services and more comprehensive reviews of prescriptions, which would allow the detection of more errors before prescriptions were processed [21, 23]. As patients admitted to the ICU are more vulnerable to medication errors and relevant adverse drug events, this could indirectly improve the quality of patient care by allowing pharmacists to spend more time on clinical work and improve medication safety [24].
Several errors were detected via other preventive measures before the patients received their medications; therefore, severe harm to patients during hospitalization was very rare [7]. In our study, all errors observed were classified as errors that did not cause harm (categories B–D). Chapuis et al. found that ADCs only reduced non-harmful errors and had no significant effect on harmful errors [6]. In this study, errors were caught through direct observation, with observers intervening when they were likely to cause patient harm. Therefore, potentially harmful errors were included in the study, even if they did not affect the patient. Most errors that could harm patients were related to nursing practices, such as administering drugs at the wrong infusion rate or route. These mistakes cannot be prevented with the use of ADCs.
AADCs have reduced medication errors; however, some issues, ADC overrides due to verbal orders, need to be addressed. Cho et al. found that two-thirds of administrative errors were related to verbal orders [25]. They pointed out that verbal orders were among the main reasons for medication errors even after the implementation of the electronic hospital system. Since verbal orders are routine practice for Code Blue, pharmacists in the United States are responsible for preparing the medicine in the code car for patients to use [11]. The participation of clinical pharmacists would be valuable to improving medication safety during emergencies; however, this is currently not feasible in several countries. ADC overrides should be assessed periodically to prevent misuse. For example, the reason for each ADC override should be documented and the ADC override medication list should be periodically re-examined [26]. These measures require pharmacists and clinical medical staff discussions to determine the specific methods suitable for each hospital.
The major strength of our study was that it demonstrated the impact of ADC adoption on prescription errors, which has been relatively under-explored in previous studies. These types of errors were not directly related to ADCs, and the reallocation of pharmacist tasks and full review of prescriptions as a result of ADC adoption may have resulted in several indirect benefits. Our study has some limitations. First, the rate of medication errors was relatively low, and some trends may not have been discernible due to the small study sample size. The primary reason for the low reporting rate was that we did not report near-miss events related to prescription and dispensing errors. However, we reported every error that occurred and established incentives and penalties to prevent non-reporting of events. Second, because the observation period coincided with the COVID-19 outbreak, the baseline characteristics of the medical center may have been affected, which, in turn, may have affected the comparability of the data. However, based on our observations, we found that the characteristics of the ICU wards were similar during the two observation periods (Table 1). This may be attributed to the less severe epidemic in Taiwan than in other countries during that period; the epidemic did not significantly affect medical care in Taiwan, as expected. Third, our findings may not be generalizable to general wards. In addition, because the observation period spun only six months before and after ADC adoption, the medical and nursing staff may not have been completely familiar with the new operational processes. If the observation period was extended, the results are likely to be different. Therefore, further studies are needed to assess the impact of ADCs in other wards over longer periods.