This blog entry summarizes the previous entry, Medical Error FMEA Risk Grids – why they are a problem.
1. Risk grids are presented whereby each cell is severity by probability of occurrence.
2. In the VA risk grid, the remote by catastrophic entry is problematic because, the remote definition is not infrequent enough (when coupled with catastrophic events) and this cell’s risk is labeled as “ok.”
a. Although this would be solved by adding another probability of occurrence row with a lower probability of occurrence, the problem would still remain if one does not quantify probabilities*.
3. The risk grids are often called semi-quantitative. This is not really true as often, no measurements or data are taken to justify the location of events with respect to probability of occurrence.
4. No matter how many mitigations are put in place, the risk of an adverse event is never zero.
a. But one can lower the risk through mitigations so that the likelihood of occurrence is so low that it is acceptable. Hence, there must always be an “ok” cell, even for catastrophic events. In any case, one can’t keep on adding mitigations forever, because resources are limited.
5. Without quantifying probability of occurrence, one is in danger of accepting risk as “ok” when it is not low enough.
6. Quantifying probabilities for all events within a process is a massive amount of work.
*Example of not quantifying probabilities. At a FMEA meeting, regarding a specific event, “I think the likelihood of that event is going to be real low. Everyone agree?, … Yeah”