The Role of Metaphor in Design

Impact on Health Outcomes

What is Metaphor?

According to Wikipedia, metaphor is defined as:

“A figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable

As described by designer Dan Saffer:

“Metaphor can be a powerful tool for designers, in both the process of designing and within the products themselves…Metaphors provide cues to users how to understand products: to orient and personify.”

For example, you may not have realized that metaphor is embedded in the design of the digital applications you use everyday. I used to take these symbols for granted, but they are totally steeped in metaphor.

When you press a button with the image of a trash can, you instinctively know that it will delete the item. When you press a button with the image of a floppy disk, you assume that it will save the item. When you press a button with the image of an envelope, you expect that the item will be sent.

Metaphor helps us understand how the world operates.

And metaphors are used not just for digital products, but also for physical products. This is the metaphor embedded in a number of medical devices that deliver injectable medications:

A pen.

When you use a pen, where do you expect the pen tip to be located? Under the cap right?

Insulin pens and regular syringes are an example of the effective use of metaphor

The needle is located where you would expect it, under the cap.

In contrast, Mylan's EpiPen is an example of a broken metaphor

The cap is located at one end and the needle is located at the opposite end. Individuals make the assumption that the needle is under the cap, inadvertently pushing their fingers directly into the needle, resulting in accidental auto-injection.

What are the Effects of Metaphor on Health Outcomes?

One recent research study from England compared the outcomes of use of different epinephrine autoinjectors.

The study population consisted of mothers of food-allergic children who were randomized to be trained on the Anapen (not available in the US) or the older EpiPen. After one year, they were randomly allocated a new device without any device-specific training. They studied 4 devices that used the broken metaphor (needle and cap at opposite ends: the old EpiPen, Anapen, the current EpiPen, JEXT), and one device with the effective use of metaphor (needle and cap at the same end: Auvi-Q). Outcomes from the study was defined as successful adrenaline administration using a trainer injector during a simulated anaphylaxis scenario.

This graph shows the success rates of epinephrine delivery across the different devices.

Mothers who used the devices with the broken metaphor had significantly lower rates of successful medication delivery (15%–67% ) compared with those who used the device with effective use of metaphor (93%)(Despite it’s good design, unfortunately, Auvi-Q was recalled and is no longer in use). As the authors concluded:

Our data clearly demonstrate that AAI device design, not simply AAI training, is critical for successful adrenaline delivery in an emergency scenario.

What is the extent of harm that has been caused by the broken metaphor of the EpiPen?

The graph below from a study by Simons et al shows the number of unintentional injections with Epinephrine Auto-Injectors by age reported to Poison Control Centers between the years of 1994 and 2007. (Note that for this analysis they searched specifically for the EpiPen product distribution code)

There were over 15,000 unintentional injections with the EpiPen reported.

Furthermore, in the same paper they describe a smaller number of unintentional injections reported by the Food and Drug Administration (n=105), and believe it or not, at least one third of those individuals who injected themselves were trained healthcare professionals. (That’s right, bad design even foils those who should know better!)

Have there been any changes to the design of the EpiPen to address the broken metaphor?

In the wake of #epigate, Mylan recently made claims that they made improvements to justify the dramatic price increases in the EpiPen, but the American Council on Science and Health recently debunked this claim:

“In May of 2016 they changed the label. It had read the same since 2008…In October of 2015 they showed that they had done post-market testing to make sure the product met quality standards…Other than that, not much has been done.”

Let’s compare older vs. the current version of the EpiPen to understand the evolution of the design.

(Some of these changes may have predated the acquisition in 2007).


The body of the pen became wider and less cylindrical.

The cap color was changed from grey to blue, and the needle area was changed from black to orange.


The text on the label changed.

Here is the comparison between old and current pens:

I am not sure that this wordsmithing would fundamentally improve safety, and besides the fact, who reads the fine text on a pen in midst of an anaphylactic reaction? (Remember Auvi-Q gave audio instructions to address this very issue?)

Finally, this was added:


The left sided photo shows the needle area of the old EpiPen. The right sided photo shows the needle area of the currently available EpiPen. On both sides of the current EpiPen, there is text on the front and back with the words NEEDLE END in large capital letters accompanied by a large block arrow. A healthcare stakeholder wouldn’t even blink at this detail, but I must quote the great Don Norman, one of the founders of human-centered design:

“Any time you see signs or labels added to a device, it is an indication of bad design.”

Instead of investing in research and development to fix the broken metaphor, Mylan is using a SIGN to prevent self-injury with the EpiPen.

This is the #sadstateofhealthcare we live with.

As I have tweeted before:

Special thanks to @foodawakenings for reaching out to the #epigate community and to @nrolves for providing me with pictures of the old EpiPen! We #makehealth as a community!

I tweet and blog about design, healthcare, and innovation as “Doctor as Designer”. Follow me on Twitter and sign up for my newsletter!

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