FDA guidelines for Unexpected Experiences

The US Food and Drug Administration has a webpage titled "Guideline for Adverse Experience Reporting for Licensed Biological Products"
http://www.fda.gov/medwatch/report/cberguid/define.htm
This guide is to be used by clinicians when reporting any adverse effects from biological products they have administered or prescribed to their patients.

Upon reading this page, I came across two terms:
"Expected Experience" and "Unexpected Experience".

The expected experience basically means the adverse effect named in the labeling or information was experienced by the user.

The unexpected experience means the patient had an adverse effect that was greater in severity of the expected experience or not listed in the labeling or information at all

If I apply this to designing a product, I would record anticipated adverse effects based on usability testing and clinical studies. If the product is launched with these known adverse effects we would expect to see a certain number of our user having the expected experience. These expected experiences would be tolerable as long as they didn't exceed the number of anticipated occurences in our target market. This would require one to be prepared to carefully track the expected experience occurences once the product is launched. In the case of an unexpected experience each one would have to evaluated.

For a simple example: Say that only 75% of tested participants were able to successfully achieve the desired outcome with the product because they were unable to complete one of the more difficult tasks. Patient eduction was performed during clinical studies and they indicate that 85% of the participants achieved the desired outcome. How do we see if that number actually plays out in the market?