July 12, 2009

Swine Flu Has Greater Impact On Obese People

U.S. researchers reported on Friday that obese people might be at risk of severe complications and death from the new H1N1 swine flu virus.

The study, published in advance in the Centers for Disease Control and Prevention's weekly report on death and disease, described the cases of 10 patients at a Michigan hospital that were so sick they had to be put on ventilators.  Three of the patients died, two of which were considered severely obese. 

The study also suggests doctors can safely double the usual dose of oseltamivir, Roche AG's antiviral drug sold under the Tamiflu brand name.

"What this suggests is that there can be severe complications associated with this virus infection, especially in severely obese patients," said CDC virus expert Dr. Tim Uyeki.

"And five of these patients had ... evidence of blood clots in the lungs. This has not been previously known to occur in patients with severe influenza virus infections," Uyeki said in a telephone interview with reporters.

Dr. Lena Napolitano of the University of Michigan Medical Center, along with colleagues, studied the cases of 10 patients that were admitted into the University's intensive care unit.  The patients suffered a severe acute respiratory distress syndrome caused by the swine flu infection.

"Of the 10 patients, nine were obese (body mass index more than 30), including seven who were extremely obese (BMI more than 40)," they wrote in their report.

The study's original intention was not to prove obesity is a special risk factor for the virus.  However, the researchers were surprised to see that seven of the 10 patients were extremely obese.

Nine of the patients suffered multiple organ failure, and five had blood clots in the lungs.

The researchers said that none of the patients have fully recovered. 

The virus first emerged from Mexico in March and has quickly spread throughout the U.S. and the rest of the world.  The World Health Organization (WHO) declared the H1N1 swine flu virus as pandemic in June.

Although the virus is causing moderate illness, all influenza viruses can be deadly. 

This virus has killed almost 500 people globally and 200 in the U.S. alone.

However, the new virus has a slightly different pattern from the seasonal flu.  The virus spreads in the summer months and attacks young adults and older children, and may affect the body slightly differently.

Uyeki said that as with H5N1 avian influenza, which only rarely attacks people, patients seem to survive better if they get Tamiflu for longer than the usual five-day treatment course.

"We don't know if it is necessary for a higher dose of the drug to be given to patients who are obese," he said.

"The high prevalence of obesity in this case series is striking," the CDC's commentary accompany the report reads.

"Whether obesity is an independent risk factor for severe complications of novel influenza A (H1N1) virus infection is unknown. Obesity has not been identified previously as a risk factor for severe complications of seasonal influenza."


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