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Influenza is the most deadly illness for the very elderly

Nearly 8 percent of patients age 85 and older who are hospitalized for influenza do not survive the disease. This death rate is more than twice the 3 percent for hospitalized patients aged 65 to 84, according to a new report by the Agency for Healthcare Research and Quality (AHRQ).

Influenza, or flu, is a contagious respiratory illness caused by viruses. Flu kills more than 36,000 Americans each year and afflicts between 5 and 20 percent of the U.S. population, according to Federal estimates. Experts endorse vaccinations though November and December since most flu activity occurs in January or later in most years.

The study also concluded that:

  • More than 21,000 people were hospitalized specifically for influenza in 2004—a 62 percent decrease from 2003, but twice the number of hospitalizations in 2001.
  • Elderly patients were the most likely to be hospitalized for influenza. Among those 65 or older, there were 28 hospitalizations per 100,000 population, a rate that is over 3 times higher than the rate for children younger than 18 (8 hospitalizations per 100,000). Among younger adults (aged 18 to 44 and 45 to 64), there were 2 to 4 hospitalizations, respectively, per 100,000 population.
  • Among those elderly patients who were hospitalized for influenza or had influenza in addition to other problems, about 75 percent were admitted through hospital emergency departments.
  • Patients hospitalized for influenza stayed an average 5.3 days, slightly longer than the 4.6 average days for other illnesses.

These statistics are from the Nationwide Inpatient Sample, a database of hospital inpatient stays that is nationally representative of all short-term, non-Federal hospitals. The data are drawn from hospitals that comprise 90 percent of all discharges in the United States and include all patients, regardless of insurance type as well as the uninsured. For more data, go to Hospital Stays for Influenza, 2004: HCUP Statistical Brief #16, at

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