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Testing, antivirals underutilized in older adults with suspected influenza
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The use of antivirals was low among older adults hospitalized with the suspected virus in urban Tennessee, despite recommendations for the early initiation of these medications, according to recent findings. Influenza testing also remained low.
“Since the 2009-2010 H1N1 influenza pandemic, the CDC has recommended prompt use of antiviral treatment for all hospitalized patients with confirmed or suspected influenza,” the researchers wrote in PLoS One. “Use of antiviral treatment among hospitalized patients has been associated with reduced mortality, with earlier treatment resulting in better outcomes.”
Mary Louise Lindegren, MD, of Vanderbilt University School of Medicine, and colleagues examined antiviral use among 1,753 adults aged 50 years and older who were hospitalized with symptoms of acute respiratory illness or nonlocalizing fever at four hospitals in Davidson County, Tennessee, between November 2006 and April 2012. Using patient medical records, the researchers collected information on how often providers tested for and diagnosed influenza as well as testing methods and the frequency of antiviral treatment. The researchers also collected nasal and throat swabs from each participant, which were tested in a research laboratory for influenza using real-time PCR. Antiviral use was defined as an in-hospital receipt of a neuraminidase inhibitor such as Tamiflu (oseltamivir, Genentech) or Relenza (zanamivir, GlaxoSmithKline); an adamantine such as amantadine or rimantadine; or experimental antiviral agents such as IV Rapivab (peramivir, BioCryst Pharmaceuticals) or IV zanamivir.
Of the 1,753 patients hospitalized during six influenza seasons, only 26% underwent provider-initiated influenza testing. Of these, 38 patients had a positive clinical laboratory test — equaling 2.2% of all patients and 8.3% of tested patients.
Despite an uptick in influenza testing after the 2009 H1N1 pandemic, testing remained low, the researchers said. Moreover, antiviral treatment without a positive influenza test was rare. Of the patients with clinical laboratory-confirmed influenza, 26.3% were given antivirals vs. 4.5% of those with negative clinical influenza test results and 0.7% of those not tested (P < .001).
The researchers wrote that most providers used rapid antigen tests, which have been shown to have poor sensitivity in detecting influenza in older hospitalized patients.
Approximately 7% of patients tested positive for influenza in the research laboratory, revealing significantly more patients who potentially could have benefited from treatment with antivirals. Of these, 0.9% received antivirals before the 2009 H1N1 pandemic, 2.7% during the pandemic and 2.8% in the post-pandemic influenza seasons (P = .046).
Research laboratory-confirmed influenza (adjusted OR = 3.04; 95% CI, 1.26-7.35) and clinical laboratory-confirmed influenza (aOR = 3.05; 95% CI, 1.07-8.71) both were independently associated with antiviral treatment. No association was observed between antiviral use and disease severity, the existence of underlying high-risk conditions, or the duration of symptoms.
According to the researchers, the availability of accurate and rapid diagnostic tests remains a barrier to the use of antivirals.
“More accurate point-of-care influenza tests could facilitate receipt of antivirals among hospitalized patients,” they wrote. “Additional strategies are needed to improve appropriate antiviral treatment among hospitalized adults with influenza, particularly for older adults with severe disease or with underlying high-risk conditions.” – by Jen Byrne
Disclosure: Lindegren reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
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