Influenza in ICD10

ICD10 Codes for Influenza

• There are 4 influenza-related codes.
• These 3 code for actual disease due to influenza:
  • Influenza pneumonia
  • Influenza without pneumonia but with other respiratory manifestations
  • Influenza with nonrespiratory manifestations
• The 4th has a long & weird name: Influenza virus NOS -- should almost never be used
  • It is an item for the pathogen list, but as indicated it is almost never needed. This is because the other three influenza items cover virtually every influenza manifestation we can think of. We've included influenza for the pathogen list only for completeness.
• Don't confuse influenza with either of: Haemophilus influenzae (H. flu) OR Parainfluenza virus
  • See: Wikipedia for types of virus included

Identifying the Presence of Influenza

• See: Influenza tracking

We have not completely decided yet, but we are considering coding influenza as Lab-confirmed, or Suspected:

• Lab-confirmed influenza
  • Present if the final result of the swab testing was positive -- even if the clinical team didn’t finally believe it was influenza
  • The tricky part here is that the hospital labs are now doing a rapid swab test (which comes back very quickly) PLUS they send the materials on to the Cadham lab were the testing is re-run. To further muddy the waters, Cadham gives a preliminary result which can be different than their FINAL result. One thing is clear -- the final Cadham result trumps the preliminary Cadham result. Thus we can’t ever make this determination until the final Cadham result is done. But what’s not clear is what to do when the rapid swab test done at the hospitals is DIFFERENT than the final Cadham result. Allan will talk to the Cadham people about that.
• Suspected influenza -- here the clinical team wrote believed that it was influenza and gave a “full course” of anti-influenza drug PLUS either: (a) no swab was sent at all, or (b) swab was sent and was negative.
  • For influenza that this not severe, the usual course of oseltamivir (Tamiflu) is 5 days. But WHO and CDC recommend that in severe cases the drug should be continued until the infection is resolved or there is satisfactory clinical improvement.
• We will talk about this more later, and take account of how Infection Control does this.

Alternate ICD10s to consider coding instead or in addition

• Haemophilus influenzae (H. flu)
• Parainfluenza virus