by Liz Mauer, MHCI
This is the third in a multipart series about how to effectively identify, understand, and communicate a product’s use-related risks.
It can be hard to know how to make use of frequency of occurrence ratings when creating URRAs.
On the one hand, the FDA (in their 2016 Human Factors Guidance), clearly states we should identify critical tasks based on the severity of the potential harm alone. Their position is that we often don’t have enough data to even hazard a guess at a frequency of occurrence. They also feel manufacturers should care about the severity of harm, however rare it may be.
However, the frequency of occurrence of a use issue is a real fact of life, and it’s difficult to even think about risk without considering the likelihood of occurrence. After all, it is a Use-Related RISK Analysis, not a Use-Related HARMS Analysis. Some use-related risks will have different potential harms, each with different severities, and these are important to understand when developing a URRA.
It’s unlikely that a product will ever be completely free of use-related risks, and the use of some products is inherently risky (i.e., using surgical tools). Reducing the harm associated with these types of products tends to make them ineffective for their intended use. How well would a scalpel work if it didn’t cut tissue? Or an electrocautery tool that doesn’t actually burn? Manufacturers are most often in the position of reducing the likelihood of a potential harm, rather than reducing the severity of a potential harm itself. It’s very hard, if not impossible, to not discuss frequency of occurrence when considering potential mitigation strategies. In most cases, reducing the frequency of a use error is the only avenue available.
The key point for manufacturers to know when trying to walk this narrow line is that you should consider frequency of occurrence when assessing potential use-related risks, but only AFTER you have done what you can to mitigate the hazard as fully as possible. By including frequency of occurrence in your residual risk discussion, you are able to give your FDA reviewer the clearest possible picture of your product’s use-related risk profile.