A Review of the Evidence on Its Safety and Benefits

Alex J. Adams; Steven J. Martin; Samuel F. Stolpe


Am J Health Syst Pharm. 2011;68(19):1824-1833. 

In This Article

Accuracy of Technicians Versus Pharmacists

Eleven published studies that evaluated the order-verification performance or error-detection capabilities of pharmacy technicians versus pharmacists were identified.[18][28] This body of research spanned more than three decades (1978–2009); the studies varied widely in their methodology, the practice settings evaluated, and the medication systems used. For an in-depth review of all the published TCT studies, readers are referred to the 2002 review by Wilson.[18]

Same-sample Studies

The following section of this article focuses specifically on three published reports on studies that assessed the accuracy or error-detection capability of pharmacists and pharmacy technicians using the same sample of medication doses (Table 1).[24–26] The reason for this focus is that a major limitation of the literature on TCT is that many published studies used different samples to evaluate the relative performance of pharmacists and pharmacy technicians;[18] "same-sample studies" such as the three summarized below allow a more meaningful head-to-head comparison.

In the literature on TCT, accuracy is defined as the percentage of orders checked that were free of errors. Accuracy is influenced by the number of actual errors in the control sample; for example, if pharmacists or technicians were presented samples with no errors and subsequently identified no errors, it might be concluded that they have flawless accuracy regardless of their actual ability to detect errors.[24] Same-sample studies mitigate this concern by analyzing the performance of pharmacy technicians and pharmacists on a level playing field. The phrase "error-detection rates" refers to the percentage of errors that are detected by the individual conducting final verification. In same-sample studies, error-detection rates allow for a direct comparison of the capabilities of pharmacists and technicians.

The first such same-sample study was conducted by Stafford[24] in a 700-bed tertiary care institution using an envelope-based unit dose distribution system. Pharmacists and pharmacy technicians were selected to participate in the study based on their normal work schedules. Pharmacy technicians were required to have at least one year of work experience and received less than two hours of training in final verification. Unit dose envelopes were filled as usual, and trays containing batches of orders were given to the study investigators. The investigators randomly introduced errors (e.g., incorrect drug, dose, or dosage form) into 2–4% of the envelopes. The batches with the introduced errors were then passed to pharmacy technicians, who reviewed each tray for errors. Any errors detected by technicians were documented (but not corrected), and the same sample of orders was presented to pharmacists. The investigators introduced 510 errors into a sample of 15,252 envelopes over a five-week period. Pharmacy technicians detected a greater proportion of introduced errors than pharmacists (97.0% versus 94.3%, respectively; p < 0.05), and the study report suggested that the task of error detection "could be safely delegated to technicians."[24]

Another same-sample study was conducted by Anderson et al.[25] in a Minnesota specialty pharmacy supplying prefilled syringes of five medications to outpatient dialysis units. Pharmacy technicians were allowed to participate in the study if they had at least six months of work experience and completed a five-hour training (the investigators did not describe the inclusion criteria for pharmacists). The syringes were prepared according to routine workflow, and both pharmacists and pharmacy technicians checked the same syringes and recorded any dose errors identified. Errors were not introduced into the samples by investigators; thus, any errors identified were naturally occurring. Over a six-month period, 10,608 syringes were checked. The investigators reported high accuracy rates for both pharmacists and technicians (99.86% and 99.83%, respectively). However, technicians in the study recorded 70 errors for syringes containing doses that were in fact within acceptable limits (pharmacists recorded 4 similar errors). In actual practice, such over-reporting could potentially disrupt workflow, as each "error" would have to be rechecked by a pharmacist. The authors did not comment on the time it took for technicians to check doses relative to pharmacists. Based on the results of the study, the Minnesota Board of Pharmacy permitted the study site to move forward with its TCT program. The authors noted that the highly specialized nature of the practice setting in which the study was conducted may limit the program's adaptability to other settings.[25]

Another same-sample study was conducted by Enderlin et al.[26] at a children's hospital. Pharmacy technicians were included in the study if they had at least one year of work experience or six months of experience as a board-certified technician. Technicians underwent a training program with both didactic and practical training components. Unit dose carts were filled according to routine procedures, and investigators introduced errors at a rate of 1 in 500 doses; a total of 19 errors were introduced into an 8645-dose sample over seven days. Both pharmacists and technicians identified 100% of the introduced errors. With regard to the accuracy of checking fills of unit dose carts (i.e., the detection of naturally occurring errors), the investigators reported an average error rate of 1.05% for technicians; the error rate for pharmacists was not reported. The authors concluded that "the use of specially trained technicians … may be a viable alternative to having pharmacists check batch." The authors noted they intended to submit their data to the Arkansas State Board of Pharmacy to consider allowing TCT in the state.[26]

Results of the 3 same-sample studies summarized here demonstrated that both pharmacy technicians and pharmacists exhibit high levels of accuracy in final dispensing verification, with 1 study finding that technicians detected more errors than pharmacists.[24] When considering the entire body of TCT research, including studies that used different samples for technicians and pharmacists, a similar pattern is observed. Wilson[18] reported that the mean ± S.D. accuracy rate reported in 11 published studies was very similar for pharmacy technicians and pharmacists (99.6% ± 0.55% and 99.3% ± 0.68%, respectively); 6 of those studies reported significantly higher (p < 0.05) accuracy or error-detection rates for pharmacy technicians.[19–24] No published studies identified in this review showed statistically significant differences in accuracy rates or error-detection rates favoring pharmacists, though this finding may be due to publication bias: Because many of the studies were conducted to convince the state board of pharmacy to permit the use of TCT, it is possible that studies showing that technicians were not as accurate as pharmacists might not have been submitted for publication.

Several reasons for the higher reported accuracy of technicians versus pharmacists were postulated. For one, technician accuracy may be enhanced by uninterrupted workflow. Verification errors by pharmacists have been attributed to multiple interruptions that reduce their focus on the work at hand.[15] Wilson[18] hypothesized that pharmacists may face more distractions or be evaluating medications for other factors such as appropriate strength or drug interactions, or that technicians may be given more time to complete the same verification process.

Study Limitations

The same-sample TCT studies described above had important limitations. The time frame for each was relatively short, ranging from seven days to six months.[24–26] It is possible that the high rates of accuracy technicians exhibited were due to the novelty of taking on a new task and that accuracy would decline after the "honeymoon" phase. Quality-assurance programs with ongoing monitoring are one strategy to prevent such regression and are a common element of most current TCT programs. Another limitation of the same-sample TCT studies was that they were conducted in tightly controlled practice settings and situations, limiting the extrapolation of the study findings to other settings such as community pharmacy settings. Finally, in all the studies, technicians received an educational or training intervention that was not provided to participating pharmacists. This difference is a limitation of trial design but not necessarily a limitation of practical application, as it mirrors existing TCT practice policies; pharmacy technicians must undergo specialized and advanced training and are subject to ongoing auditing through quality-assurance programs, whereas pharmacists are not subject to similar rules in most practice settings.

Another limitation of the same-sample TCT studies is that they did not characterize the type and severity of errors missed by technicians and pharmacists to determine any differences between the two groups. Insights into this issue may be gleaned from two previous TCT studies in which different samples were used to test pharmacists and technicians. Becker et al.[20] reported that no categories of errors were exclusive to pharmacists and pharmacy technicians, and the errors judged to be more serious (e.g., incorrect drug) occurred at similar rates among pharmacists and technicians (0.04% for both). Similarly, Spooner and Emerson[23] reported that there was no difference in the rate of detection of high-risk errors (e.g., wrong drug) between pharmacists and pharmacy technicians (p > 0.25).

Lastly, the same-sample studies did not analyze the time and resources it took for technicians and pharmacists to complete the verification process. Gmerek and Ashby[21] found there was no significant difference in the time required for pharmacy technicians to check a patient's medication drawer compared to pharmacists (0.76 minutes versus 0.77 minutes), which suggests that delegating this task to pharmacy technicians should not increase the resources needed to complete the task.

Impact on Pharmacists' Clinical Activities

The impact of TCT programs on augmenting pharmacists' availability for clinical services was evaluated in four studies that reported the amount of time saved by pharmacists or the types of patient care activities pharmacists were able to enhance as a result of TCT programs (Table 2).[12,19,25,28] Though these studies relied on either pharmacist self-reporting or estimation, they indicated that pharmacists practicing in TCT models gained additional time for patient care activities. The reported time savings ranged from 10 hours per pharmacist per month to 1 hour per pharmacist per day (more than 30 hours per pharmacist per month). In a 2008 report, McKee[12] described a multiphased implementation process for his facility's TCT program, noting that the pharmacist time savings would likely increase with the expansion of the scope of TCT to include medication cart filling in addition to the refilling of automated dispensing machines.

A preliminary report on the outcomes of clinical pharmacy activities enabled by TCT was presented to the California Board of Pharmacy in 2006.[30] In a 48-week study period, pharmacists intercepted 1296 errors: 68% at the prescribing phase (most commonly, wrong dose, allergy contraindications, and necessary medications not ordered) and 32% during the administration phase (most commonly, omission of dose, transcription error, and wrong dose). Of these prevented errors, 422 (33%) were judged to have the potential to cause harm to the patient; 23 errors could have led to an increased length of hospital stay, 11 could have caused permanent harm, and 1 could have resulted in death. Pharmacists provided additional services to the health care team, including dosing medications on request and providing drug information. Since those numbers were reported only as a presentation to the pharmacy board, there is little information regarding the study design and methodology, and it is unclear how many of these medication errors might have been intercepted in the absence of TCT.[30]


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