If you review the raw data documentation and any accompanying research papers, you will be informed that "event_key" is meant to be an important field.

Master Event Data: A distinct master event data record will be present for each source reporting anevent. In other words, if a User Facility, Distributor, Manufacturer, and voluntary submitter all report an event, there will be four event records. These individual source records are related via the EVENT KEY. EVENT KEY is an internally-generated key which links multiple sources to a single event.


However from both the API queries and text file downloads the event_key field seems to be completely empty. Documentation also has missing details to help answer the question. Hope to get a response on this!

1 Answer 1


It appears that the EVENT_KEY is blank for each and every MAUDE record in the source data themselves, which is why it is also blank in openFDA. The following grep command was used to confirm this:

grep -oP "(?m)^\d+\|\w*\|" mdrfoi.txt mdrfoithru2019.txt mdrfoiadd.txt mdrfoichange.txt | grep -oP "\|.*?\|" | grep -oP "[[:alnum:]]+"

  • Hi Denis, thanks for confirming - this was the case I noticed as well. I am trying to understand if this would represent any issues as the documentation states that even_key plays quite a large role in joining the files together (although you can join on mdr_report_key, I am unsure if this would represent the same view as stipulated in the documentation) Commented Jun 4, 2020 at 8:11
  • I think the files are in fact joined only by mdr_report_key. event_key just links multiple events together in case multiple sources reported the same device event. Commented Jun 4, 2020 at 15:34

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