Some years ago, I suggested that the FMEA tool in use at the Institute for Healthcare Improvement was not very good. So I went back to see if anything has changed. The answer is no.
Somewhere on the IHI site, you can find (you probably have to be logged in) a success story: East Alabama Medical Center Opelika, Alabama, USA. If you click on this link you will see that the “RPN” for a chemotherapy medication process has been greatly reduced. Here’s the problem:
To review: in a FMEA process, one lists potential failure modes as:
Failure Mode – a description of the failure
Cause – a description of the cause
Effects – a description of the effect
For each item, one lists the following in a traditional FMEA
Probability – the likelihood that the failure will occur
Severity – the consequences should the failure occur
Probability and severity are each given numerical values on a scale of 1-10 (typically) and multiplied together to get a risk. All of this is explained in the ISO document on risk management for medical devices ISO 14971.
There are certain features of FMEA which readily become apparent. The failure modes with the highest severity usually have the lowest probability of occurrence (10×1) = 10. If one concentrates on the total of these high severity low probability items, one sees that there is no way to reduce the number – severity will always be at 10 and probability is already at 1.
IHI introduces a third term, R the likelihood that the failure will not be detected and gives this a number on the 1-10 scale so the “RPN” number is the multiplication of three values. This is totally bogus because detection is already contained in likelihood of occurrence. But with the IHI scheme, one can now get a reduction in R and hence a reduction in the total value and claim that the process has been improved.