Instructions for Use – Why we cannot use them as the sole mitigation for risk
Instructions for Use
Why we cannot use them as the sole mitigation for risk
Risk mitigation. Human Factors engineers want risk mitigations to be added into the device design. Device engineers want the mitigations to be added to the Instructions for Use (IFU). Which is the preference? Which is best? Which is correct?
Today we’ll use a prefilled syringe (PFS) as an example. While a combination product, the context below is applicable to medical devices as well. When I refer to “device,” this is all encompassing of medical devices and combination products.
Background of Risk Control
Per ISO 14971:2019 and EU MDR/IVDR, there is a hierarchy of risk control, with a prescribed order of implementation. First is inherent safe design and manufacture, followed by protective measures in the device and manufacturing, and lastly information for safety and training.
Risk mitigation first and foremost starts with the device design and manufacturing processes. When new risks are identified, the device design or manufacturing process should be updated to control and mitigate these risks. This is referred to as inherent safety by design and manufacture. Implementing this may be easier for designing novel devices, which allow for changing design and manufacturing options as they are new, but what if the device is our PFS example? One cannot simply remove the needle to prevent inadvertent needle sticks – the PFS will no longer function as intended.
If there are no updates that can be made to the design or manufacturing process to control and mitigate the risk, the next level of risk control is implementing protective measures in the device or manufacturing process. For a PFS, a manufacturer can add ancillaries to the device, for example an automated needle safety device. This will prevent the syringe from being accessible to anyone after use, thereby reducing the likelihood of the risk of an inadvertent needle stick.
The last measure of risk controls is information for safety and training. Information for safety is captured in the IFU and labeling. For the PFS, a manufacturer could include a sharps warning. But why isn’t that enough? Why is it preferred to add something onto the device instead of simply adding a warning in the IFU?
IFU as a Risk Control
IFUs – a regulatory requirement and colorful leaflet we spend so much time and money to update and test; just to watch users open the box, set them to the side, and try to figure out how to use the device without once reading the IFU.
The primary challenge with relying on the IFU for risk mitigation is simple – it requires the user to pick it up and then read it. If users don’t select and read the IFU, they will not see information like a sharps warning, regardless of how clear the warnings may be. But if there is an inherent design or protective measure like an automated needle safety device, the feature will work regardless of if the user reads the IFU.
Integrating the Human Factors Engineering Process into Design
In order to give themselves the best chance of developing effective risk control measures, project teams should integrate the Human Factors Engineering (HFE) process into the product design and development. The HFE program should begin during early device design, and should be performed iteratively, just like the design process. Figure 1 below is a common diagram for iterative device development. How do we apply the HFE process to this?
Figure 1: Generic Iterative Design Process
To integrate the HFE process into the iterative design process, the first step is to get the HFE team onto the project team from the beginning. This way the team as a whole can plan appropriately and ensure they are all aware of the interactions needed between the device design team and the HFE team, as should be identified in the project plan or Design and Development Plan (Figure 2). From here, the HFE team makes their own plan and then creates the Context of Expected Use Document and User Interface Specification as the Planning and Requirements part of the iterative design loop (Figure 2)[1]
Figure 2: Planning and Requirements – HFE Deliverables
During the Analysis and Design part of the design loop, the HFE team will create the Task and Use (T&UE) Analysis and Use-Related Risk Analysis documents (Figure 3). For the Implementation, the team will create the IFU and training material (Figure 3). Note: for the first few iterations of this loop, there may not be training material. Using this feedback loop is a great way to determine if training is needed.
Figure 3: Analysis & Design and Implementation: HFE Deliverables
The next step is Testing, which is what most people think of when they think HFE. Many see the summative validation evaluation as a final checkbox before a regulatory submission. However, this is far from the case, as can be seen since summative validation studies are not listed in the Testing list in Figure 4. Depending on the device, many iteration loops will be needed based on the risks identified in both the URRA and the use errors observed during these studies. Exploratory/generative and ethnographic studies are great ways to discover the nuances of both your device and your user groups. Formative studies, during later iteration loops, help determine if the risks previously identified have been mitigated.
Figure 4: Testing: HFE Deliverables
The Evaluation step takes the data collected from the studies and feeds it back into the greater device design system (Figure 5). This step asks if new risks or use errors were identified, leads to an update of the risk documentation with these new data, and leads to a path forward to mitigate these new risks. For the most effective risk mitigation, and to comply with the standard, the first path should be to update the device design before updating the IFU and labeling.
Figure 5: Evaluation: HFE Deliverables
Once you reach this step, if updates are to be made, then you repeat the loop, updating documentation as you go, until the design and manufacturing process have mitigated the risks as far as possible. Any additional risks that are mitigated by the IFU and other labeling still must be tested to ensure the risks have been reduced as far as possible.
When all the risk controls have been established, then the final planning is for the summative validation evaluation. For this, all risk documentation needs to be updated, and commercial devices, IFU, and labeling are needed. This leads out of the iterative design loop, into development, where the summative validation evaluation takes place (Figure 6).
Figure 6: Development: HFE Deliverables
When executed appropriately, the HFE process helps the device design team control and mitigate risk at the device level prior to submission and market release, reducing the likelihood of post-market events.
I will leave you with one last example to show why using the IFU to mitigate risk may not the be best choice. Let’s say a manufacturer has a training program for the patients and uses training and the IFU as the sole risk mitigation. Let’s imagine the product is a rescue medication, such as an epinephrine autoinjector. What if the patient who received the training is unconscious and a good samaritan becomes the user and has never seen an autoinjector before? The good samaritan will not have been through the training, and the likelihood the patient has been walking around with the IFU taped to their autoinjector doesn’t seem very high. Developing risk control measures into the autoinjector itself increase safe and effective use, and reduce overall risk.
References
[1] For details on the HFE deliverables referenced, see our January newsletter.
About the Author:
Stephanie Canfield, MS
Stephanie is a Senior Consultant in Human Factors Engineering at and the Quality Manager at Agilis Consulting Group and is active on standards committees and industry groups for medical devices and combination products. In her current role, Stephanie manages projects of varying complexity for both medical devices and combination products, preparing various documentation and executing HF evaluations. Stephanie integrates risk management and human factors to support successful regulatory submissions and ensure regulatory compliance.
Stephanie has a Master of Science in Biology and over 10 years of experience in academia and industry. Stephanie has practical experience in a range of areas, from product feasibility, research and development, process validation, quality engineering, and human factors engineering throughout the IVD, medical device, and combination product space.