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Chapter 43. Prevention of Misidentifications
Heidi Wald, M.D.
University of Pennsylvania School of Medicine
Kaveh G. Shojania, M.D.
University of California, San Francisco School of Medicine
Subchapter 43.1. Bar Coding
Machine-readable automatic identification (ID) systems,
including bar codes, magnetic stripes, optical character recognition and
radiofrequency labeling, have improved productivity and quality in diverse
industries. Bar codes represent the oldest and most common of these
machine-readable ID systems,1,2 and are widely used in industrial
manufacturing, shipping and inventory tracking operations. Prior to bar coding,
these processes would have involved keystroke entry of identification numbers,
producing approximately one error in every 300 entered characters. In contrast,
bar coding produces misidentification errors at rates ranging from one character
in 15,000 to one character in 36 trillion.3
The use of bar coding in healthcare was first described over 30
years ago in clinical laboratories and blood banks.1,4 In 1984,
Rappoport identified 3 areas for the use of automatic ID technology in lab
medicine: patient identification, document identification, and specimen
identification.1 However, in a 1987 survey by the American Hospital
Association, the use of bar codes was most widespread in materials management
departments, rather than in clinical application.5 Other areas in
which hospitals employed bar codes at that time included the clinical
laboratory, pharmacy, radiology, medical records and asset management. Despite
the Health Industry Bar Code Council's call for standardization in the
mid-1980s, the implementation of bar code technology has been stymied by lack of
industry standards and failed cooperation among all
As bar coding has the potential to substantially increase
productivity and accuracy, one would expect it to be applied to important
patient safety practices. Unfortunately, the published literature contains very
little evidence regarding healthcare applications. In this chapter we focus on 4
areas in which bar coding shows promise for improving patient safety: patient
identification, medication dispensing and administration, specimen handling, and
medical record keeping.2,7-10
Machine-readable patient ID systems could replace conventional
wrist-banding, and might reduce patient ID errors ranging from specimen
collection to medication and blood product administration. Attempts to create
such machine-readable ID systems were reported in the blood banking literature
as early as 1977.11 Transfusion Medicine is particularly attuned to
issues of patient identification, as specimen collection and blood product
administration account for the majority of preventable transfusion
Most scenarios for patient identification involve the
substitution or supplementation of the traditional wristband for one with a
unique bar code patient identifier. All patient specimens, medications and
released blood products then receive the patient's unique bar code ID. No
procedure or treatment can occur unless the patient's ID is scanned with a
portable scanner and matched with a bar code generated by the doctor's order.
For example, a phlebotomist would carry the scanner, check the patient's ID
against a bar coded specimen label or collection list, and draw blood only in
the event of a match. Similarly, for administration or treatment, the patient's
ID and the intended therapeutic would be scanned at the bedside with a portable
reader. If a match exists, the transfusion or medication is allowed and the time
and date are recorded and even transmitted directly to the hospital computer
system. The nurse's bar code ID can also be scanned and a timed administration
record can be created. If there is no match, an alarm is sounded, and the
administration delayed until the problem is resolved. 9,14
Other technological means to reduce error in patient
identification have been examined in the transfusion literature. Several
researchers explored the use of a system providing a mechanical barrier to
transfusion through a series of locks.15 This system appears to be
cumbersome and easily circumvented. In addition, electronic blood banking, with
point-of-care crossmatching and computer-controlled release of blood, has been
examined for high volume transfusion areas such as the operating room or
intensive care unit.16 Due to major barriers to large-scale
implementation, these practices will not be discussed further.
Clinical laboratories have integrated bar codes in specimen
handling with a great deal of success.3,8 Several authors have
described the development of central laboratory information systems (LIS) that
employ bar code technology. Collection list and label software can be modified
to integrate and produce bar coded information. Confirmation of labeling and
patient ID occurs at the bedside. Specimen sorting and aliquoting in the
laboratory can be shortened or eliminated by various setups. At
Rush-Presbyterian Hospital in Chicago, a central receiving station rapidly sorts
and aliquots bar coded samples as they move on a conveyor belt.3 At
the University of Kansas Medical Center, the collection tubes are also used for
analysis, thus eliminating the need for aliquoting samples. Additionally, the
computer sends the bar code-coordinated orders to each of the 2 chemistry
analyzers. Because a sample can then be appropriately processed at either
analyzer, the need for sorting samples has also been eliminated.8
Clinical labs also employ bar code technology in harder-to-automate processes.
For instance, the University of Utah uses bar codes to replace common keystrokes
for text reporting of microbiology results—e.g., a technician might use a bar code
"pick list" to scan the single bar code that means "no growth for 24 hours" and
eliminate the need to type this phrase.17,18
Medication dispensing and administration
The use of bar codes is uniquely suited to the dispensing and
administration stages of the medication process.19 Bar coding may be
used to simplify the patient cassette (the medicine tray for bedside
delivery) filling and verification process.20 For instance, a
technician fills a cassette according to a computerized, bar coded medication
schedule and completes a quick verification by scanning the label of each
unit-dose that has been placed in it with a handheld scanner. The computer can
generate an error message if an incorrect medication is entered. The
administration of bar coded medications can also be tracked at the point-of-care
using a portable scanner and compared against the hospital computer's medication
orders.9,21 Bar coded medication administration has the added
capability of creating a record of the administration (i.e., RN, date, time) and a
bill. This type of system could be integrated with a patient identification
system in an attempt to eliminate errors resulting in administration of
medication to the wrong patient.
Medical record keeping
Radiology and medical records departments use bar code
technology to track the location and status of studies and
charts.22-24 Even more creative use of bar coded information has been
reported in the emergency medicine and pharmacy literatures. As with the
applications in the microbiology lab, bar codes can be used to replace
frequently used text for the creation of medical records. "Pick lists" of bar
codes with their text equivalents can be employed in circumstances requiring
speed and accuracy. Several uses of bar coded scripts have been examined in
resuscitation events, and in mass casualty recording.10,25-27 The use
of bar code "pick lists" for the documentation of pharmacists' clinical
activities has also been explored.28-30
Prevalence and Severity of the Target Safety Problem
Bar code technology may be used to address any number of
patient safety issues in medicine. For this discussion, we will define the
target safety problem as patient identification in general, using transfusion
medicine as a specific example.
Patient identification remains a challenge in hospitals because
of the number of complex interventions that occur to patients ranging from meals
to surgeries. These interventions occur in a variety of locations and are
provided by large teams of staff who work in shifts. In addition, sick patients,
or those who have a language barrier, are not always capable of responding to
questions about their identity or treatment plans. Hospitals generally rely on
standardized wristbands containing the patient's name and other identifying
information such as medical record number or date of birth. Unfortunately,
conventional wristbands are not reliable sources of patient identification. A
1991 national sample of 712 hospitals estimated error rates for conventional
patient identification wristbands to be 5.5%.31 In half of the
errors, the patient's wristband was absent altogether. The error rates were
significantly lower in hospitals where phlebotomists had responsibility for
monitoring wristband accuracy, as the phlebotomy staff would not perform routine
lab work unless the band was corrected. Other errors included more than one
wristband with conflicting data (18.3%); wristbands with incomplete (17.5%),
erroneous (8.6%), or illegible data (5.7%); and rarely, patients wearing
wristbands with another patient's data (0.5%). As patient identification data
are only as good as the information entered at registration, the use of bar
coded ID data could not be expected to correct certain types of errors such as a
wristband with incorrect data entered at admission, although it is potentially
beneficial in eliminating other types of errors such as illegible data.
Even when wristbands are free of errors, protocols for patient
identification (such as dual witness verification of identification for blood
transfusion) are easily circumvented or performed incorrectly.32 In
an analysis of major transfusion errors reported to the FDA over a 10-year
period from 1976-1985, Sazama found 10 patient deaths where the actual and
intended patients shared the same last name, and 5 deaths where the 2 shared the
same hospital room.13 Consequently, automatic patient identification
systems have been proposed as a technological solution to remove human factors
(Subchapter 41.1) from the patient identification process.
Despite technical improvements in testing for blood group
identification, fatal ABO-incompatible transfusions in the United States
continue to occur at a rate ranging from approximately 1:600,000 to 1:800,000,
with as many as two dozen fatalities in the US annually.12,13 Thus,
the chance of a patient suffering a fatal transfusion reaction due to
ABO-incompatibility is roughly equivalent to the risk of acquiring HIV infection
from a blood transfusion.33,34 Patient misidentification represents
the most common cause of ABO-incompatible transfusion, accounting for 46-57% of
these errors.12,13 Since the rate of patient and donor having blood
group compatibility by chance is approximately 60%, it is estimated that
the total number of ABO-incompatible transfusions is much higher than the rate
of fatal errors. A study from New York State estimated that as many as one in
12,000 transfusions involve administration of a blood product intended for
another patient or release of blood of an incorrect group.12
Opportunities for Impact
The implementation of automatic patient identification may
present a large opportunity to bring transfusion medicine and other hospital
interventions closer to the goal of zero risk. According to a survey conducted
by the American Society of Hospital-System Pharmacists, 1.1% of responding
hospitals use bar coding of drug products in conjunction with bar coding on the
patient's identification tag.35
Multiple reports of the use of bar codes appear in the medical literature,
but most of these relate to inventory management. Few authors examine bar codes
for patient identification. Only one of these studies was a prospective
evaluation, and in the study bar coded patient identification comprised only one
small part of the intervention.10 One observational study examined a
bar code patient ID system for medication administration.9 In the
study, however, routine patient ID scanning was easily circumvented and the
actual error rate was not provided. The remainder of the reports are descriptive
in nature.14,36,37 Therefore, error rates in automated patient
identification could not be readily compared to usual practice.
The use of bar coding in other clinical care applications
(aside from inventory control) has been examined prospectively in trauma
recording27 and in documenting pharmacists'
interventions.28 One additional observational study examined bar
coding in pharmacy dispensing.20
Some of the studies report error rates in transfusion or
medication errors (Level 2), while others report related outcomes such as speed
of data entry (Level 3), transcription errors (Level 2) in a variety of
experimental and clinical settings, and user satisfaction (Level 3).
Evidence for Effectiveness of the
A point-of-care information system for medication management
was implemented at a tertiary care center in Colorado.9 The system
provided online patient and medication data that verified medication
administration at bedside using hand-held scanners to record patient ID, nurse
ID, and medication unit-dose bar codes. When intervention data were compared
with historical controls, the pre-intervention medication error rate of 0.17%
dropped to 0.05%, sustained over 3 years for an overall decrease of 71% (p value
not reported). There was a 33% decrease in "wrong drug" errors, a 43% decrease
in "wrong time" errors, and a 52% decrease in "omitted dose" errors. There was a
47% decrease in "transcription/order-entry" errors. There was no change in
"wrong patient" errors or "wrong dosage" errors, perhaps because the component
of the multifaceted intervention most likely to mitigate these errors, the use
of the scanners for patient ID, was easily and frequently circumvented. It is
unclear if bedside scanning added an unwanted layer of work for the nurses, or
if they were uncomfortable performing this task in front of patients and
families. Computerized pharmacy and bar code tracking of medications led to
qualitative improvements in documentation time, scheduling of administration,
nursing-pharmacy communications, and pharmacist drug monitoring. However, the
contribution of bar coding to the decreased error rate is not distinguishable
from that of the entire intervention. It also appears that the point-of-care
patient ID portion of the intervention was easily bypassed, and was therefore
not adequately evaluated.9
On a large medical ward of a university hospital, the satellite
pharmacy was reconfigured to implement bar code technology for drug
dispensing.20 The hospital bar coded all medications, patient
medication cassettes, patient wristbands, and employees. Standard dispensing
time was estimated at 8.24 seconds, while dispensing time for bar coded
medications was 6.72 seconds (p value not reported). Accuracy of the standard
cassette fill system was 99.6% (equivalent to one error in 250 doses), while the
accuracy of bar coded cassette fill was reported to be 100% (based on 0 errors
in about 20,000 doses). The pharmacists were freed to do other work as the
burden of dispensing was shifted to pharmacy technicians.
As pharmacists have begun to use bar code technology for
medication distribution, 2 pharmacy groups described the use of bar codes in
recording their clinical interventions.28, 29 One group found bar
code documentation to have lower overall error rates compared to manual
documentation, while the marginal cost of implementing bar coding was less than
$100 (factoring in savings in labor costs related to manual entry).28
These data were limited by the small number of operators who differed on their
preferences for manual versus bar code recording.
A prospective trial reviewed bar code technology in trauma
recording. Experienced emergency room nurses found bar coded pick lists to be
easy to use and produced fewer errors per record compared with handwriting
(2.63 ± 0.24 vs. 4.48 ± 0.3,
p<0.0001) for videotaped trauma resuscitations.27 In a prospective
study of simulated mass casualty incidents in The Netherlands, bar coded
computer registration produced 25% fewer inaccuracies than handwritten medical
The limitations of these studies are numerous, including their
small sample sizes and lack of generalizability. However they demonstrate that
bar code technology is generally easy for operators to use, can be applied in a
variety of creative ways, and produces easy-to-demonstrate gains in accuracy and
Potential for Harm
There is no clear detriment to patient identification with a
bar code system. However, as with the addition of any new technology, the
possibility exists that the complexity of the information system, especially if
it grows, could create more routes for potential failure. For instance, an error
during patient registration might be perpetuated throughout the hospitalization
by the information systems, and be more difficult to correct than with
conventional systems. The system's data are only as accurate as that entered by
Costs and Implementation
Significant barriers need to be overcome before the full
potential of bar coding can be exploited in the clinical setting. The process of
medication dispensing and administration highlight several examples of these
barriers. First, pharmaceutical manufacturers have yet to adopt a universal bar
code standard like the UPC system used in grocery store inventory.38
As of yet, there has been no regulatory mandate by the FDA to serve as an
incentive, although the American Society of Hospital-System Pharmacists recently
urged the FDA to take action.39 Second, placing bar codes on
unit-doses of medications often requires major changes in packaging (such as an
increase of the package size to accommodate the bar coded label). Bar code
tracking systems would have difficulty with unusual doses such as halved
tablets. IV doses would still require bar code labeling in the pharmacy when
At this point, implementation of bar coding requires a
commitment on the part of the hospital to relabel every unit-dose of medication
using a hospital standard. The hospital pharmacies that have implemented these
systems have repackaged and relabeled many unit-doses at considerable
cost.9,20 One health system estimated costs at $119,516 annually,
with the per dose costs of bar code labeling estimated at 2.73
cents.20 The bottom line is that, at present, the costs of
implementing bar coding in an entire pharmacy inventory are significant and the
The use of bar coding in simpler clinical scenarios (i.e., using
a blood transfusion wristband for patient identification) may be implemented
with very modest outlay of resources (estimated to be less than 5 cents per
wristband).36 The costs of the scanners themselves are moderate. A
new model scanner, software and recharger were priced at about $1100 in
Bar coding is a fast and accurate method of automated data
capture that in experimental settings provides qualitative improvements in speed
and accuracy of data entry. Bar code technology might be creatively applied to
any number of data-driven processes in medicine. As the rapid and accurate
transfer of data is paramount in healthcare, the thoughtful application of
appropriately piloted and evaluated bar code technology is likely to be well
received and deserves further investigation.
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