Flu patients 85 or older face higher death rate

WASHINGTON (Reuters) - The flu kills nearly 8 percent of patients aged 85 and older if the virus makes them ill enough to go to the hospital, according to U.S. government statistics released on Tuesday.

And it kills 3 percent of patients aged 65 to 84 hospitalized with the illness, said the Agency for Healthcare Research and Quality, or AHRQ.

The report, taken from a database of records on hospital stays, found that more than 21,000 people were hospitalized specifically for influenza in 2004.

In 16,000 more cases, hospital records showed the patients had influenza in addition to another illness for which they were admitted.

The U.S. Centers for Disease Control and Prevention says influenza kills 36,000 Americans in an average year and sends 200,000 to the hospital.

"I don't think it is a contradiction," said Anne Elixhauser, a senior research scientist at the AHRQ who led the study. "What we are doing is we are presenting just a component of what the CDC does."

The CDC tracks "influenza-like illnesses" during flu season and bases its estimates on reports from hospitals around the country.

"What we have got is just those hospitalizations that are specifically coded for just influenza," Elixhauser said in a telephone interview.

She said her team's numbers correlated well with CDC reports.

"In 2001 we recorded 19,400 hospital stays for influenza," she said. "The CDC was reporting that was a very mild flu year. But in 2003 we found 86,300 hospital stays, and that was a very severe year."

The U.S. Midwest has the highest rate of flu hospitalization among the elderly, at 11 per 100,000 population. Western states have the lowest rate, at 2.8 per 100,000.

The circulating flu viruses change slightly each year, and between 5 percent and 20 percent of the U.S. population becomes infected each flu season.

The CDC says more than 100 million doses of flu vaccine are available this year and recommends that everyone over 50, pregnant women, young children and people with chronic diseases get vaccinated each year.