Interesting article about how many people really die from the "regular" flu each year:
A Pandemic of Confusion About Flu's Death Rates The CDC's Figure of 100 Influenza Deaths a Day Is Flawed, but That Doesn't Stop People From Spreading It
By CARL BIALIK
MAY 13, 2009
http://online.wsj.com/article/SB124217724145913411.html
Though the swine flu captured the world's attention, its total confirmed death toll of fewer than 100 people so far provided a point of comparison that many health experts couldn't resist: Garden-variety seasonal flu kills that many people each day in the U.S. alone.
That's according to Ted Epperly, president of the American Academy of Family Physicians, which is among many groups that cite an estimate from Centers for Disease Control and Prevention scientists that flu causes or contributes to an average of 36,000 deaths each year. "This is no little deal," Dr. Epperly says. "I don't want people to think, 'Oh my gosh, we just avoided this bullet with swine flu,' when every day influenza kills 100 people."
But a bullet, it turns out, may never have left the barrel. According to the CDC's own numbers, influenza was listed as the underlying cause on just 849 death certificates in 2006, the most recent year available -- half as many as hernias and a quarter the number killed by peptic ulcers. This number has been flat in recent decades even as the CDC's much larger estimates of annual flu deaths have been increasing.
This discrepancy in death counts highlights a fundamental, and possibly unavoidable, flaw in national health surveillance. The CDC tallies the toll of diseases and injuries using death certificates, but these often are filled out by harried physicians with incomplete information. "Sometimes they're not going to know," says Robert Anderson, the chief of mortality statistics for the CDC's National Center for Health Statistics. "Sometimes they may need to guess. Sometimes they're not willing to guess."
The resulting death counts are often unreliable. Even if they were accurate, though, some public-health officials prefer measures that take into account age at death and survivors' quality of life. Such alternate measures might de-emphasize influenza. According to the CDC's estimates, 91% of all flu victims in the decade through 2003 -- the latest available data -- were 65 or older.
"It's a quick way to get policy makers and the lay public to understand the potential impact," David Shay, a CDC flu researcher, says of the 36,000-death figure he helped estimate, "but it shouldn't be the only measure."
These measurement problems are particularly acute with influenza, because it can exacerbate underlying conditions such as heart disease or precipitate pneumonia or other respiratory illness. The doctors, coroners or medical examiners who fill out death certificates are supposed to list an underlying cause of death, but Dr. Anderson says many who die from the flu never see a doctor. If they do, flu tests are rare because the doctor is focusing on the complication caused by flu.
Dr. Shay and colleagues attempted to compensate for this perceived underreporting of flu deaths by looking for clues in seasonal mortality patterns. If flu's human toll is uniquely resistant to measurement, it is also uniquely measurable by statistical sleuthing, according to Dr. Shay. That's because flu's activity varies each year, in time of onset, duration and severity.
More interactive graphics and photos In a paper earlier this year, he and his co-authors unveiled four different statistical models for measuring flu deaths. Some of these models made use of lab tests from around the country, correlating the fluctuation in positive flu-test results with the waxing and waning in respiratory and circulatory deaths. All four models came up with similar estimates: Tens of thousands of people dying each year from the flu. One of the models produced a 10-year average through the 2002-2003 flu season of 36,171, the basis for the 36,000 figure now ubiquitous in public-health campaigns and media coverage.
This estimate has its skeptics. It's based on lab testing of people who primarily are ill, and not a representative sample of the population, Jimmy Efird, a statistician with the University of North Carolina's Center for the Health of Vulnerable Populations, points out. And it makes use of the same death-certificate data whose flaws necessitated the research, potentially replicating the errors.
Peter Doshi, a graduate student at the Massachusetts Institute of Technology, has gone further in his critique. In a 2005 article in the British journal BMJ provocatively titled "Are US flu death figures more PR than science?" Mr. Doshi criticized the CDC for sometimes confusing deaths caused by the flu with those where the infection was one contributing factor. In an article last year, Mr. Doshi compiled recorded deaths from the flu for the past century and found that the numbers in years of notable outbreaks within the past 60 years weren't that different from years just before and after them.
Dr. Shay defends his measurements but acknowledges they aren't exact, noting, for instance, that his models don't take into account temperature and air pollution, which themselves can affect the incidence of respiratory illness.
If people make decisions based on faulty information, says Mr. Doshi, "then this is important and needs fixing."
Improving the understanding of global disease burden has been a priority in public health for several decades, and part of that effort is finding a better tool than body counts to measure diseases. To decide on priorities and measure progress, groups such as the World Health Organization have begun to contemplate a measure called disability adjusted life years. DALYs take into account both the number of years lost -- so deaths of children count more than those of the elderly -- and the quality of life lost when sickness or injury doesn't kill but leaves lasting effects.
Calculating the relative burden of, say, blindness (about a 60% diminution of quality of life) may seem cold calculus, but in allocating limited public-health resources, that's how decisions sometimes are made.
More troubling is just how hard it is to come up with DALYs, which add nuance to death tolls but also devilish complexity. Dozens of countries lack reliable death-registration systems, and assigning weights to disabilities is subjective.
The fundamental premise behind DALYs is also problematic. Someone who dies in middle age, for example, may have fewer years of life remaining than a newborn, but he or she likely has more financial responsibilities, including keeping family members healthy.
Should DALYs be embraced at the CDC, they might lead to a de-emphasis on the flu. Many people who die of flu-related causes are old and sick and may not have lived much longer. Colin D. Mathers, coordinator of the WHO's mortality and burden of disease unit, compares flu's yearly toll to the tens of thousands of deaths attributed to the 2003 heat wave in Europe. Many were quite ill already. "If the heat wave hadn't occurred, they probably would have been dead in six months, anyway," he said.
Dr. Shay says he'd like to find more sophisticated ways of expressing the burden of flu even though he recognizes this might mean the waning of the flu's relative prominence. "We need to express the impact in a variety of different ways," Dr. Shay says, "so people can make the best decisions."
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BTW is there spell check on this thing? hmmm diabetes? diabetis? diabeties ? lol
