A spectrum of problems with using
From the November 13, 2003 issue
In our July 24, 2003 issue, we provided an example of how
color-coding can contribute to medication errors. Specifically,
we mentioned how a color-coding system for the pharmacologic
class of ophthalmic medications, along with similar corporate
logos, fonts, and package sizes, have led to numerous errors
with these products. Antiinfectives are tan, steroids are
pink, mydriatics and cycloplegics are red, beta-blockers are
yellow, and so on. But individual products and dosage strengths
within the class are not color-coded, so mix-ups have been
widely reported within each class.
Since publication of that article, we have received several
questions that reflect unresolved issues about the use of
color to reduce the risk of errors. To fully understand the
issues, the distinct differences between color-coding, color
differentiation, and color matching need to be explored, as
well as how each may be applied by end-users and manufacturers.
Color-coding. Color-coding is the systematic, standard
application of color to aid in classification and identification.
A color-coding system allows people to memorize a color and
match it to its function. The black cap used in the US for
all vials of potassium chloride concentrate injection is one
example. No other products can use black caps. Thus, practitioners
can assume that a manufacturers vial with a black cap
contains potassium chloride concentrate, as long as the color
black has been memorized to mean potassium chloride.
Color differentiation. Color differentiation, on the
other hand, entails the use of color to make certain features
stand out, or to help distinguish one item from another. To
cite an example, a vaccine product for adults may be packaged
in an orange box while the same companys pediatric formulation
may be packaged in a light blue box. However, the color itself
is not a standard code that is applied systematically to classify
and identify the product, as it is with color-coding.
Color matching. Color matching is also used sometimes
to reduce the risk of errors. For instance, a medical device
may have a blue plug that attaches to a blue receptacle and
yellow plug that attaches to a yellow receptacle. However,
the colors have no special meaning beyond matching one item
Frequent problems with color-coding. Color-coding
for pharmaceutical products should be used with extreme caution,
as there are several problems associated with its widespread
adoption. For one, theres a limit to the variety of
discernible colors available for commercial use. Well demonstrated
in color-coding research in other industries (1,2) subtle
distinctions in color are poorly discernible unless products
are adjacent to each other. Contrast with background or surrounding
colors also can be problematic if a certain color must be
used for product identification. And of course, clinicians
might be color-blind, resulting in possible misidentification
of color-coded products. This could be the reason that FDA
and the pharmaceutical industry have frowned on color-coding
for the most part.
Next, color-coding has not been scientifically tested as
a way to prevent medication errors. But, like any change,
theres evidence that it may actually contribute to some
errors that would not happen without it. As mentioned above,
color-coding ophthalmic products by pharmacologic category
has led to numerous errors. Another example is the recent
change in the colors used to identify needle gauges on disposable
syringes. Several 10-fold insulin overdoses have been reported
because the 25 gauge needles on some tuberculin syringes are
now coded in orange, a color previously associated with insulin
syringes (see our March 6, 2003 issue).
Color-coding can also be error-prone if its not applied
consistently across the industry, or within a single manufacturers
product line. For example, one company used product-specific
color-coding schemes for the labels on some of their products,
and yellow and blue labeling for the remainder of their products.
On occasion, practitioners have mixed up some of the products
with blue and yellow labels, failing to recognize that the
blue and yellow labels were not a product-specific color code.
Weve also observed occasional problems with user-applied
color-code schemes. For example, a color code from the American
Society for Testing and Materials (ASTM) is employed as the
basis for user-applied labels on syringes. The label color
identifies a drug category, but it does not necessarily identify
a specific drug, strength, or dose contained in a syringe.
So anyone other than the person who prepared the syringe may
not be aware of its actual contents, and thus administer the
wrong drug or dose. Of course, if the system is used as intended
to quickly distinguish the different drug classes, the ASTM
color scheme has merit. However, the user should add the actual
drug name (if its not already printed on the label)
Less frequent problems with color differentiation.
Color differentiation also has not been scientifically proven
to prevent medication errors. However, practitioners favor
it for commercial use to help reduce the risk of product-selection
errors within a manufacturers product line. The idea
is for users to efficiently find and select medications from
storage areas using color differentiation, then carefully
read the label for verification. But users dont always
read the labels, or they may suffer from confirmation bias
and fail to see that they do not have the correct product
in their hand.
However, color differentiation has been used successfully
in commercial applications to enhance recognition of various
label elements by making the information stand out. For example,
a product warning using the color red is more likely to be
seen if the products primary label is black and white.
On occasion, weve also suggested using a yellow highlighter
to draw attention to important label information, such as
the concentration of the drug, or the total volume of product
in the vial.
Occasional problems with color matching. Likewise,
little scientific evidence exists to prove the value of color
matching related to medication use or pharmacological products.
In fact, its rarely, if ever used for such purposes.
However, its benefits appear sound when applied to the use
of medical devices, given that the user or manufacturer applies
the proper colors to products.
Black and white labels. Of course, if all products
had identical black and white labels and were packaged in
the same size and shape, careful reading of the labels would
be the only way to differentiate them. Perhaps this would
reduce error potential, but its not likely to happen
in our free enterprise system for marketing pharmaceuticals.
We look forward to the time when all products are bar-coded
or identified through radio-frequency methods. Then, well
be better able to store them all together but tell them all
apart, even if we misread or misunderstand the label.
1. Christ RE. Review and analysis of color-coding research
for visual displays. Human Factors 1975;17:542-570 (web.engr.oregonstate.edu/~pancake/cs552/guidelines/color.coding.html).
2. American National Standards Institute, Association for
the Advancement of Medical Instrumentation. Human factors
engineering guidelines and preferred practices for the design
of medical devices (ANSI/AAMI HE-48). Arlington, VA: Association
for the Advancement of Medical Instrumentation, 1993; pg.