How Should Influenza in Patients With Asthma Be Treated

Patients with asthma who have suspected or confirmed influenza should be strongly considered for antiviral medications because of their increased risk of developing a complication of influenza, said researchers from American Academy of Allergy Asthma&Immunology. Data from randomized controlled trials for antiviral medications for patients with asthma are limited; 1 trial demonstrated a decreased risk of asthma exacerbation (defined by changes in peak flow) in the oseltamivir group compared with placebo but did not meet its primary endpoint of demonstrating a difference in time to freedom from illness. Patients with asthma who present with concerning signs and symptoms of lower respiratory tract infection and suspected influenza should be treated with antiviral medication even if more than 48 hours have elapsed since symptoms started. In addition, patients with asthma should be treated for asthma exacerbation per their personalized written asthma action plan. Complications of influenza infection such as bacterial pneumonia should be considered. Evaluation of fatal pediatric 2009 H1N1 influenza cases found Staphylococcus aureus to be the most common bacteria isolated (including some cases of methicillin-resistant S aureus).

Antiviral medication choice depends on the influenza strain type and resistance patterns. Strain type can be obtained directly from test results (if the RT-PCR technique is used) or can be estimated by community surveillance reports. Seasonal influenza A H1N1-type (not 2009 H1N1) is resistant to oseltamivir, whereas type A H3N2-type is not. The influenza type B strain that circulated in the 2008 to 2009 season was susceptible to oseltamivir. Two of the type A strains that circulated most in the 2008 to 2009 season are expected to circulate in the 2009 to 2010 season and are included in the 2009 to 2010 seasonal influenza vaccine. Current recommendations are based on 2008 to 2009 season circulation and resistance data and will be updated when additional data become available. Oseltamivir is recommended for influenza B, influenza A H3N2-like, and 2009 H1N1. Zanamivir or a combination of rimantadine and oseltamivir is recommended for influenza A seasonal H1N1-like because of oseltamivir resistance. If the chosen testing method does not distinguish between influenza A strains, a
combination of oseltamivir and rimantadine is recommended for patients with asthma. If novel H1N1 influenza is the dominant circulating strain and antiviral resistance does not emerge, oseltami- vir may become the recommended antiviral for strains that cannot be confirmed. Zanamivir is active against all currently circulating influenza strains but should be used cautiously in patients with asthma because of case reports of severe bronchospasm.
Oseltamivir is the preferred antiviral medication for pregnant patients and children <7.> Patients with asthma who are not vaccinated against influenza at the time of diagnosis should be offered vaccination with TIV (for seasonal or 2009 H1N1) along with antiviral treatment.
Those with fever should not be vaccinated until the fever resolves.


Conclusions and key points for patients with asthma:

• Vaccinate with seasonal and 2009 H1N1 TIV unless there is a strong contraindication such as current febrile illness or Guillain-Barre´ syndrome within 6 weeks of previous influenza vaccination.
  

• Patients with asthma concerned about influenza vaccine allergy (including a convincing clinical history of egg allergy) should be evaluated by an allergist/immunologist.
  

• Consider whether testing for influenza will change treatment recommendations; when testing, strongly consider the RT-PCR testing method.
  

• Treat asthma patients with antiviral medications based on circulating strains and resistance patterns.