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It's time for my seasonal teaching on flu, antivirals, and what they teach us about the principles of conservative prescribing! 1/
Which of these is more accurate when diagnosing flu in clinic? 2/
Rapid flu swabs have a sensitivity of 50-70%, and a specificity of >90%, so false negatives are common, esp during the flu season. 3/
https://www.cdc.gov/flu/professionals/diagnosis/labrolesprocedures.htm
https://www.cdc.gov/flu/professionals/diagnosis/labrolesprocedures.htm
Meanwhile, clinicians have a broad range of accuracy depending on the study, population, and setting, ranging from sensitivity of 40-70%, and specificity of >90%. 4/
For both clinicians and rapid tests then, we have many false negatives, but few false positives. 5/
What symptoms are most indicative of flu? 6/
The combination of fever, cough, and acute onset had an LR of 5.4; fever LR of 3.8, and chills, malaise LR 2.6.
https://jamanetwork.com/journals/jama/fullarticle/200419
7/
https://jamanetwork.com/journals/jama/fullarticle/200419
7/
It's important to accurately diagnose the flu for infection control, anticipatory guidance, and to identify complications. But what about antivirals? 8/
The CDC has recommended neuraminidase inhibitors (oseltamivir and zanamivir) for the treatment of influenza. The basis of these recommendations primarily comes from industry-sponsored clinical trials, which have been widely criticized for lack of transparency. 9/
A Cochrane review of published AND unpublished data from the manufacturers, meanwhile, found that on average, antivirals shortened flu duration by less than one day, and did not reduce transmission, hospitalization, or complications.
https://www.cochrane.org/news/tamiflu-and-relenza-getting-full-evidence-picture
10/
https://www.cochrane.org/news/tamiflu-and-relenza-getting-full-evidence-picture
10/
Meanwhile, this review and others have found that kidney injury, vomiting, and psychosis increased when patients took antivirals, and that these were initially under reported in published trials. 11/
For this more unpleasant but slightly shorter course of flu, the cost is 100 dollars for tamiflu out of pocket. 12/
When I bring up these concerns, the answer is often, but what else do we have to offer? It is difficult for providers and patients to end a clinical encounter without a prescription. 13/
This phenomenon was beautifully described in "The Principles of Conservative Prescribing: "In striving to relieve suffering and prolong life, we often turn to medications." 14/ https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1105913
One of the most important articles of the last 20 years. In short, the authors advise be skeptical, wait for evidence, educate yourself with neutral sources, and do not rush to treat with ineffective medications. In other words, forget the tamiflu. 15/15
*Remember that flu replicates almost exclusively in the respiratory tract and that in adults, GI symptoms are rare.
