I do a bit of German --> English proofreading / translation of medical studies here in Berlin. We've had a bit of a running debate about perioperative mortality vs perioperative lethality. In German, die Letalität is used to describe the number of people who die as a result of an operation. Apparently die Mortalität is the wrong word for this.

In English it is my feeling that it's the other way round - perioperative mortality seems correct whereas lethality is only really used to describe things or processes which are intended to kill (virus, gun, disease etc.) I don't feel it is appropriate for describing the rate of unintended deaths as a result of operations.

What's interesting is that a Google search for "perioperative lethality" returns hundreds of thousands of hits almost exclusively from German / European authors writing in English. I think we have discovered a classic example of insitutionalised "Denglish". What are people's thoughts on the various usages?