Influenza in ICD10

We are aware that the instructions in this article are different from our old definition and from the tmp projects. Please do not use these instructions at this time. We will get back to them in January when everyone is back from vacation. In the meantime, please use the following instructions: 
* Influenza treated
* Influenza tracking

ICD10 Codes for Influenza

There are 4 influenza-related codes we're using in ICD10.

• 3 code are 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 (see more info in that article)
• 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

• It's not always simple. The reason is that the value of lab tests in helping us figure out whether a person has influenza depends on: (a) how long after onset of symptoms the test was done, (b) which test was done, (c) whether the sample was upper or lower respiratory, and (d) whether the test is done in the midst of flu season, at the start of flu season, at the end of flu season, or not at all during flu season.

NEW Definition - Dec 21.17 - THE BOTTOM LINE: How We Will Diagnose Influenza

• During established flu season (see below for more on flu season identification), the diagnosis of influenza is mainly clinical. So, lab confirmation is not needed to make the diagnosis.
• If the clinical team thinks it’s flu, and they’re treating with a full course of oseltamivir (Tamiflu) or any other anti-influenza agent, then consider influenza as present, regardless of the results of any influenza tests, done in hospital labs or Cadham.
  • A full course of Tamiflu is 5 days for mild disease. However, for severe influenza (including requiring mechanical ventilation), the current recommendation is to continue it until the patient has begun to improve.
• Template:Discussion what if the patient died or got discharged before getting full course of drug?Trish Ostryzniuk 16:19, 2017 December 21 (CST)

• Completely off flu season (warm months, before there is any reported flu in the province, and after the flu season has been declared to be over) -- a person will be diagnosed as having influenza ONLY if the FINAL CADHAM test result is positive. Said another way, in the absence of a positive final Cadham test for influenza, during these time periods we consider influenza as absent, regardless of clinical suspicion, treatment for flu, and rapid test results.
• The hard part is right at the start and end of typical flu season. In this case, use the following algorithm:
  • One or more lab tests were done (including rapid tests in hospital labs, and Cadham tests) and any of them were positive -- then consider influenza to be present.
  • No lab tests were done, but the team says they think it’s flu, and they’re treating with a full course of tamiflu, then consider influenza to be present.
• also used for Influenza tracking

Figuring Out Where We Are in Influenza Season

• There are no rigid rules about when flu season starts and ends. While generally flu season is during cold weather, the precise start and end differs every year.
• Generically, flu season starts once there have been laboratory-confirmed cases in the community, and ends after there are no more positive laboratory test results for it.
• Manitoba Health has a weekly report during cold weather months about this the status of flu season: https://www.gov.mb.ca/health/publichealth/surveillance/influenza/index.html

Alternate ICD10s to consider coding instead or in addition

• Haemophilus influenzae (H. flu)
• Parainfluenza virus

Template:CCMDB Data Integrity Checks

None yet. Do we need any? Possibly with Template:Discussion

• Influenza virus
• Pharm influenza drugs
• Dxs
  • old: Tracheobronchitis
  • new (see above)

• caution about putting a cross check with influenza drugs, as there are times when a patient is given the med for suspect influenza however, the Cadham lab report comes back as negative.
  • Best to wait until we have some data to do this. Tina has scheduled review with Julie for 3rd week of November.

Possible checks:

• if there was a confirmed tmp entry, there has to be a dx
  • maybe no drug and if DC treat or comfort care?
• if there is a dx... can't do any cross checks in old dx because tracheobronchitis isn't always influenza, right? Might work with the new dxs, though, they are influenza specific
• if there is a drug... are they ever used for anything else? would coding for influenza go away if lab comes back clean? Might not be able to do anything with the drugs.