Which Flu Patients Need Antiviral Meds?

I didn't originally intend on making it viral syndrome week here on MidlevelU, but given the season it seemed appropriate. After my shift the other day in the emergency department, I felt the need for an influenza brush-up. So, I'm passing on the relevant and lesser known tidbits to other nurse practitioners who could also use a refresher. Yesterday, we looked at influenza testing and its accuracy (see 5 Lesser Known Facts to Help Make a Flu Diagnosis). Today, we'll take the next step in the patient care process and look at treatment. 

Patients commonly ask me for prescriptions when they're sick, even when over-the-counter, or even no medication at all, is probably their best bet. As nurse practitioners, we're well aware that Tamiflu is commonly prescribed for influenza but that it has its limits. Which influenza patients actually need a prescription for an antiviral medication? Here are some F.A.Q. that will help. 

How effective is antiviral therapy in treating influenza?

Overall, Tamiflu has been shown to shorten the course of influenza symptoms by one-half to three days. The benefit of the medication is the greatest if given within the first 24 to 30 hours of symptom onset and in patients with fever at presentation. That being said, most studies of the drug's efficacy only involve patients who have been sick for less than 48 hours which could skew data.

While studies show that Tamilfu shortens the course of influenza, the jury's still out on it's efficacy as far as disease severity. Some studies suggest that antiviral therapy reduces the severity and incidence of influenza complications. Others have not demonstrated this benefit. 

Which patients do not need antiviral therapy?

Adult patients younger than age 65 with mild influenza and who are not at high risk for complications do not require treatment for influenza, although it may be considered. Treatment with antiviral medications should not be given in these low risk patients if they have been ill for more than 48 hours. Patients with mild, uncomplicated influenza are unlikely to benefit from antiviral therapy if initiated more than 48 hours after symptom onset. Finally, patients who are recovering from influenza do not require antiviral therapy. 

Which patients do need antiviral therapy?

In general, nurse practitioners should treat individuals who meet any of the following criteria: 

  • Confirmed or suspected influenza who are severely ill (ex. oxygen desaturation, lower respiratory infection, tachypnea, dyspnea) and those who show signs of clinical deterioration
  • Patients at increased risk of complications with confirmed or suspected influenza that present within 48 hours of symptom onset
  • Patients with mild illness who are not at increased risk of complications and that present within 48 hours of symptom onset (optional) 
  • All pregnant women with suspected or confirmed influenza, even those who present more than 48 hours after symptoms begin if they are not yet improving

Who does need postexposure prophylaxis?

Patients often request antiviral medications if a close contact or family member contracts influenza, even if they themselves are not yet sick. But, when is this really necessary? Here are the guidelines: 

  • Vaccinated patients at high risk for complications who have been exposed to an individual with influenza in the past 48 hours when there is a poor match between the vaccine and the circulating virus strain do require prophylaxis. 
  • Unvaccinated patients at high risk for complications who have been exposed to an individual with the flu in the past 48 hours should receive prophylaxis. They should also be vaccinated against influenza.
  • Healthy unvaccinated adults, healthcare workers and children older than one year who have been exposed to influenza and who are in close contact with an individual at high risk for influenza complications should receive post exposure prophylaxis. 

If you decide your patient is a candidate for post-exposure prophylaxis, antiviral therapy should be continued for 14 days. Prophylaxis should only be started if antivirals can be initiated within 48 hours of exposure.  

Who does not require postexposure prophylaxis?

In general, patients who are not at risk for influenza complications and who are not in close contact with individuals at high risk for influenza complications do not require postexposure prophylaxis with antiviral therapy. This is especially true for vaccinated patients in a season where there is a good match between the vaccine and circulating strain do not require prophylaxis (exception: residents of long-term care facilities). 

Which patients qualify as at high risk for complications?

There are several groups at high risk for influenza complications. These include:

  • Children less than 5 years old, especially those less than 2 years of age
  • Adults older than 65 years of age
  • Immunosuppressed individuals
  • Women who ae pregnant or postpartum (2 weeks or less)
  • Children and adolescents receiving long-term aspirin therapy
  • Native Americans and Alaskan Americans
  • Extremely obese (BMI greater than 40) 
  • Residents of nursing homes or long-term care facilities
  • Individuals with the following medical conditions: asthma, chronic lung disease, kidney disease, liver disease, blood disorders, endocrine disorders, metabolic disorders, neurologic conditions

Have you prescribed postexposure prophylaxis for your patients this flu season?

 

Sources: 

Treatment of Seasonal Influenza, UptoDate

Influenza Antiviral Medications: Summary for Clinicians, CDC

 

Comments

I had a question about the recommendation for post-exposure prophylaxis. The article states "If you decide your patient is a candidate for post-exposure prophylaxis, antiviral therapy should be continued for 14 days. Prophylaxis should only be started if antivirals can be initiated within 48 hours of exposure". Which resource did you find that is recommending a 14 day course of prophylactic treatment? UpToDate recommends once daily dosing of Tamiflu for 7 days for prophylaxis and twice daily dosing of Tamiflu for 5 days for treatment.

Just curious...

Jennifer