Guidance on Medical Device Patient Labeling:- Appendix E

Warnings and precautions:

The purpose of this section is to:

• define and explain the terms warnings and precautions,
• discuss their use in medical device labeling,
• recommend approaches to effective presentation based on literature and research findings, and
• present some of the common issues associated with warnings and precautions.

Note: Labeling a device with warnings and precautions is the least preferable method of controlling accidents and injuries. You should make every effort to design the device so that the hazard is eliminated. Only when this is clearly impossible should you resort to a warning or precaution in the labeling. For instance, if the device may be made without toxic substances, this would be the preferred alternative.

What are warnings and precautions?

Warnings and precautions are written, pictorial, and/or audible alerts to a hazard. The term used to identify the particular hazard presents the reader with a cue to the seriousness of the hazard.

A warning alerts the reader about a situation which, if not avoided, could result in death or serious injury. [ANSI Z535.4-1998] It may also describe potential serious adverse reactions and safety hazards. The designation of a hazard alert as a "warning" is reserved for the most significant problems. The term WARNING is generally used as the signal word for this type of hazard alert. If a problem may lead to death or serious injury, FDA may expect you to highlight the warning by placing it in a box.

The term precaution is used for the statement of a hazard alert that warns the reader of a potentially hazardous situation which, if not avoided, may result in minor or moderate injury to the user or patient or damage to the equipment or other property. [ANSI Z535.4-1998] It may also be used to alert against unsafe practices. This includes the special care necessary for the safe and effective use of the device and the care necessary to avoid damage to a device that may occur as a result of use or misuse. The word CAUTION is generally used as the signal word for a precaution statement.

The distinction between warnings and precautions is a matter of degree of likelihood and seriousness of the hazard. The target audience for medical device labeling (health care practitioners and lay users of home use devices) generally recognize a hierarchy of hazard alerts, with warnings being those of a more serious nature and precautions being of a less serious, but important, nature.

What is the purpose of warnings and precautions in medical device labeling?

The basic purpose of a warning or precaution is twofold:

• to inform users of potential personal and environmental hazards, and
• to persuade them to modify their behavior to avoid injury or device damage.

For a warning or precaution to be effective, readers must:

• perceive the threat to be both severe and relevant to them,
• believe that they can perform the recommended response, and
• believe that response will be effective in avoiding the hazard.

Effective warnings and precautions capture the reader’s attention, are understood, are consistent enough with the reader’s beliefs and attitudes to be accepted, and are persuasive enough to motivate the reader to comply. They invoke an appropriate level of fear arousal, conveying the nature and extent of the hazard, without being so strong that they backfire, causing the reader to select an alternative action or no action.

What is appropriate content of an effective warning or precaution?

There are four elements generally recognized by the courts and research (See References – Warnings and Precautions) as necessary for an effective warning or precaution:

• a signal word (WARNING, CAUTION) to alert the reader that what follows is important hazard information. A symbol or icon may emphasize the effect of the signal word. Additional enhancement, such as bolding, larger type, underlining, italics, or color may help the information stand out from the rest of the text. However, studies have demonstrated that a large difference in font size between the signal word and the text may de-emphasize the importance of the text and therefore reduce the likelihood that the text will be read.
• a hazard avoidance directive in the form: Do Not, Never, Avoid..." (or Do, if more appropriate) followed by the action to avoid (or perform). The objective of this directive is to give clear instructions to the user on how to avoid the hazard.
• a clear statement of the nature of the hazard associated with the warning (e.g., allergic reaction to material, strong magnetic field) or precaution (e.g., environmental effect, damage from resterilization) that characterizes the severity and the likelihood.
• the consequences, specifying the serious adverse events, potential safety hazards and limitations in device use that result if users do not follow instructions. The purpose is to give them a clear idea of the risk, which is likely to increase compliance. Hazard alert research has shown that this element has a significant effect on readers. If the consequences are not included, the alert is likely to be less effective.

The signal word should appear first. The order provided here for the other three elements (hazard avoidance, hazard identification, and consequences) will be appropriate for most instances, but may be altered as necessary to best communicate the information to the reader.

How is an effective warning or precaution formatted?

No magic formula works in every instance. The writer must apply the principles discussed here for writing effective warnings and precautions as appropriate to the user and the device.

We suggest that you present warnings and precautions in "clusters" of issues that provide the reader with the information in the most logical and usable order for the particular device. For instance, a surgical device may have the warnings and precautions grouped, or clustered, into Preoperative Information, Intraoperative Information, and Postoperative Information, with appropriately highlighted headers. A home use device may have warnings and precautions grouped according to Setup, Calibration, Use, Storage, and Disposal. There are many possible groupings of this important hazard avoidance information, including the use of a "Before You Start" subsection for devices deemed to need a select and very limited group of warnings and precautions to be read before the device is handled at all. Within each cluster, we encourage you to prioritize the information by clinical significance. If there are no logical clusters or groupings of the hazard information, arrange warnings and precautions in order of clinical significance.

Warnings and precautions should be as concise and focused as possible while providing sufficient information. We recommend using bullets, rather than full sentences. Each bullet should contain a single item. We recommend against grouping a number of warnings or precautions in paragraph form. Users are more likely to read and comply with warnings or precautions presented in outline form using plenty of white space and consistent indentations, rather than paragraphs.

Additional approaches that can assist readers to notice, understand, and comply with warnings and precautions include:

• Integrating warnings and precautions into the task/hazard-related context. This increases the chance that the reader will encounter the information when he is most receptive to it.
• Using concrete rather than abstract terms and jargon. Frank language makes the writing more interesting and therefore more likely to be remembered. For example, say "Contact with this product will produce severe burns" rather than "Contact with this product will result in serious injury."
• Using the simplest possible construction.
• Making each warning and precaution conspicuous. The use of white space and simple highlighting techniques can call attention to the warning or precaution. Do not bury this important information in extensive text.
• Standardizing terms and formatting across the labeling and, if possible, across products to increase consumer recognition.

Where should warnings and precautions be placed for maximum effect?

Research shows that hazard alerts are most effective when integrated into the task information at the most relevant location. Medical device labeling has traditionally contained separate sections for warnings and precautions. This approach predates much of the research into hazard alert effectiveness. However, there is a reluctance to abandon the placement of this important information in separate sections in medical device labeling because of user familiarity with this format. Some research has shown that short, well-highlighted warning messages can actually get users to read a set of longer, more detailed warnings in another section of the labeling. We recommend that warnings and precautions included in the separate sections be those that can be taken out of procedural context and still be effective.

Procedurally related warnings and precautions that cannot be taken out of context should be located with the associated procedural step. Research differs on the most effective location relative to relevant text, but placement immediately before the associated procedural task has been shown to be effective. We suggest considering this approach for warnings and precautions that are included in procedural instructions.

What other issues should be considered in designing warnings and precautions?

Because it is difficult to get readers to notice and read warnings and precautions, it is important to know what works with the target audience of the particular device. This is most effectively done by testing draft warnings and precautions on a sample of the target audience. Recommended testing points are when the labeling is being designed and again after it has been implemented. The latter testing can provide information to be used at the next labeling change.

Including too many warnings and precautions, over-warning, dilutes the strength of all of the hazard alerts. We recommend that writers use care in what is designated as a warning or precaution. Careless designation can have the same diluting effect as over-warning (e.g. "WARNING! Batteries not included."). Repeated exposure to unnecessary hazard alerts (not relevant or already known) reduces the effectiveness of the important warnings and precautions.

We know that readability indexes can predict, but do not measure the reader’s actual ability to comprehend labeling. Because of the complexity of the process by which individuals interact with hazard alerts, you should not rely on readability indexes to predict warning and precaution comprehension.