Antiviral drugs improve H1N1 flu outcomes

Kathleen Blanchard's picture
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According to a review of hospital admissions to ICU and deaths from H1N1 flu in 2009, seventy five percent of deaths from H1N1 swine flu have been seen in patients with one or more underlying health conditions. The study looks at patients hospitalized within 24 hours of onset of flu symptoms from April 2009 to mid-June 2009, finding that asthma, diabetes, heart, lung, and neurologic diseases, and pregnancy were associated with the majority of admission to ICU from H1N1 swine flu - but not all. The study authors also suggest that antiviral medications could improve H1N1 outcomes, and are an important consideration, even for those not hospitalized but are at high risk for complications.

According to the report, “Antiviral drugs were administered to most patients, but such therapy was started more than 48 hours after the onset of illness in a majority of the patients. Delayed initiation of antiviral therapy may have contributed to an increased severity of illness”.

The study, published in the New England Journal of Medicine examined 272 patients with H1N1 swine flu. Twenty five percent of patients were admitted to ICU – seven percent died. Forty percent of patient admitted for H1N1 flu had pneumonia on chest X-Ray. The average age of patients with pneumonia from H1N1 flu was 27. The average age of ICU admissions for H1N1 swine flu was age 29.

The findings show that H1N1 flu resulting in ICU admissions and deaths occurred primarily among young adults during the first two months of the flu pandemic. Pneumonia was the cause of death in seven percent of cases. Most patients had underlying health problems contributing to the severity of H1N1 flu and death. However, young healthy adults were also found to develop severe symptoms from H1N1 swine flu.

The study authors say antiviral drugs, given within 48 hours of H1N1 swine flu symptoms can reduce the severity of symptoms, making it important to seek treatment early for flu symptoms.

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The study authors say young adults are more susceptible to the ravages of H1N1 flu, compared to those over age 65. Just five percent of hospitalizations occurred among older adults.

A review of H1N1 flu deaths early during the pandemic suggests that antiviral therapy may reduce the severity of symptoms, even if initiated more than 48 hours after the onset of symptoms. For patients with signs of pneumonia on chest x-ray, antibiotics are recommended. Unfortunately, healthy young adults with no underlying medical problems were also found to develop severe H1N1 flu symptoms.

The authors write, “Data from our study suggest that the use of antiviral drugs is beneficial, especially when initiated early, since patients who were admitted to an ICU or died were less likely to have received such therapy within 48 hours after the onset of symptoms. Despite the absence of definitive data regarding clinical effectiveness, treatment with antiviral drugs should be initiated in hospitalized patients with suspected 2009 H1N1 infection, even if such therapy is initiated more than 48 hours after the onset of symptoms, especially in patients with pneumonia and outpatients who are at increased risk for complications, including pregnant women”.

Symptoms of H1N1 flu reported included fever, and cough. Thirty nine percent of those studied had diarrhea or vomiting. Individuals admitted to the hospital, over age 65, had an underlying medical condition one hundred percent of the time. Asthma was the most common underlying medical condition resulting in hospital admission for H1N1 swine flu in children and adults, a condition that unfortunately has become highly prevalent.

Outcomes of H1N1 flu were consistently more positive when antiviral drugs were given. The authors write... “the only variable that was significantly associated with a positive outcome was the receipt of antiviral drugs within 2 days after the onset of illness”. Oseltamivir (Tamiflu) was recently approved under an Emergency Use Authorization by the FDA.

Doctors are urged to consider H1N1 influenza in any patient with respiratory illness, pneumonia, or fever in order to better understand H1N1 swine flu treatment and outcomes. Additionally, the authors say antiviral treatment should not be withheld even if H1N1 flu symptoms have been present more than 48 hours. “Empirical antiviral treatment for hospitalized patients with suspected influenza or pneumonia and for outpatients who have underlying medical conditions or who are pregnant should be considered”.

Reference: NEJM

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