I thank Thompson, Shay, Weintraub, Brammer, Meltzer, Cox, and Bresee from the
U.S. Centers for Disease Control and Prevention for their letter of 18
Jan,[1] and I am happy to note their interest in engaging in
constructive dialogue. I also want to thank Engelbrecht,[2]
Mehta,[3] and Crowe,[4] whose letters raise
additional concerns regarding the reliability and basic assumptions of current
official U.S. (and German[5]) estimates of influenza-associated
mortality.
While Thompson et al. (CDC) and Simonsen et al. (NIH) are both critical of my
paper, neither address my article's[6] major criticisms. For clarity, I will
summarize them here: First, the rationale behind the supposedly unique
relationship between flu and pneumonia is questionable; Second, the CDC's
estimates of an 80% increase from 20,000 to 36,000 influenza-associated deaths
are not supported by a 30% decrease in recorded flu deaths over the same period (table);
Third, the CDC continues to misrepresent its estimates of influenza-associated
mortality as recorded flu deaths.[7]
Thompson et al. state that I "made several errors of fact," but do not quote my
paper to document which of my statements, if any, were inaccurate. In addition,
Thompson et al. write that "[Doshi] suggests that they [the death figures] are
deliberately exaggerated in order to increase the use of influenza vaccine." I
made no such claim, and debate over motivations only serves to sidetrack
this discussion. Rather, I referenced flu shot campaign literature which shows
that current statistics are being leveraged to increase flu
vaccination.[8]
There has been much discussion regarding the question of whether population
figures support the CDC's increases in flu-associated death estimates. The
CDC's "Influenza Model" (shown in Table 2 in their paper[9])
estimated an average of 18,715 annual flu-associated deaths occurred during the
1980s. (This figure supports the previous official estimate of
20,000.[10]) For the 1990s, their model estimated 35,271 annual
deaths. Thompson et al. state that the 65+ population increased 64% and 85+
population has "more than doubled" from 1972 to 1999 and "can indeed explain,
in part, why influenza-associated deaths have increased." However, it is only
logical to compare rising flu-associated mortality estimates with population
data over the same time period--the 1980s to 1990s. Here, without further,
model-independent ways to ascertain and verify the risk of flu-associated death
across all age groups, it remains undetermined and implausible that the
population increases are sufficient to explain the 88% rise in CDC estimates.
(See table.)
Table: Yearly averages over the 1980s and 1990s.
1980s
1990s
Percent change
Current CDC model, estimated
flu-associated deaths, all ages[9]
18,715
35,271
88%
Recorded flu deaths, all ages[11]
(ICD9 487, ICD10 J10-J11)
1702
1197
-30%
Population, 65+[12]
28,165,119
33,472,890
19%
Population, 85+[12]
2,622,438
3,667,187
40%
Proportion, 85+ to 65+
0.09
0.11
18%
Thompson et al. ask for dialogue "on how best to refine these [CDC] estimates."
One suggestion would be to correct the widespread misrepresentation of
statistical estimates of flu-associated mortality as recorded flu deaths. In
their letter, German officials voiced the need to "always use correct
terminology",[5] and I think much can be gained from this advice. A
second suggestion would be to make clear to the public the assumptions built
into the CDC model, as well as the dangers such assumptions portend. For
example, the basic assumption that influenza is responsible for the majority of
seasonal excess deaths is controversial,[13] and weekly regression
analyses, as Simonsen et al. pointed out, "are in danger of being confounded by
other seasonal factors."[14]
I think discussion would be best served by focusing attention back to the
questions regarding the statistical inconsistencies in official flu-associated
mortality estimates.
Peter Doshi
References:
Thompson WW, Shay D, Weintraub E, Brammer L, Meltzer M, Cox N, Bresee J. "Are estimates of influenza-associated deaths in the US really just PR?". BMJ [rapid response] (18 Jan 2006) <http://bmj.com/cgi/eletters/331/7529/1412#126308> (retrieved 21 Jan 2006).
Buchholz U, Schelhase T, Haas W, Uphoff H. "Why do official statistics of 'influenza deaths' underestimate the real burden?". BMJ [rapid response] (2 Jan 2006) <http://bmj.com/cgi/eletters/331/7529/1412#125150> (retrieved 21 Jan 2006).
Doshi P. Are US flu death figures more PR than science? BMJ 2005;331:1412.
"An average of about 36,000 people per year in the United States die from influenza." Quoted from: CDC, "Influenza: The Disease" <http://www.cdc.gov/flu/about/disease.htm> (retrieved 12 Jan 2006).
Thompson WW, Shay DK, Weintraub E, et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003;289:179-186.
CDC. "Prevention and Control of Influenza Recommendations of the Advisory Committee on Immunization Practices (ACIP)" MMWR (April 12, 2002); 51(RR03);1-31. Available online: <http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5103a1.htm>. (Retrieved 21 Jan 2006).
Dushoff J. Assessing influenza-related mortality: comment on Zucs et al. Emerging Themes in Epidemiology 2005 Jul 21;2:7.
Dushoff J, Plotkin JB, Viboud C, Earn DJD, Simonsen L. Mortality due to Influenza in the United States--An Annualized Regression Approach Using Multiple-Cause Mortality Data. Am. J. Epidemiol. 2006;163:181-187.
Rapid Response:
Author's reply #2
I thank Thompson, Shay, Weintraub, Brammer, Meltzer, Cox, and Bresee from the
U.S. Centers for Disease Control and Prevention for their letter of 18
Jan,[1] and I am happy to note their interest in engaging in
constructive dialogue. I also want to thank Engelbrecht,[2]
Mehta,[3] and Crowe,[4] whose letters raise
additional concerns regarding the reliability and basic assumptions of current
official U.S. (and German[5]) estimates of influenza-associated
mortality.
While Thompson et al. (CDC) and Simonsen et al. (NIH) are both critical of my
paper, neither address my article's[6] major criticisms. For clarity, I will
summarize them here: First, the rationale behind the supposedly unique
relationship between flu and pneumonia is questionable; Second, the CDC's
estimates of an 80% increase from 20,000 to 36,000 influenza-associated deaths
are not supported by a 30% decrease in recorded flu deaths over the same period (table);
Third, the CDC continues to misrepresent its estimates of influenza-associated
mortality as recorded flu deaths.[7]
Thompson et al. state that I "made several errors of fact," but do not quote my
paper to document which of my statements, if any, were inaccurate. In addition,
Thompson et al. write that "[Doshi] suggests that they [the death figures] are
deliberately exaggerated in order to increase the use of influenza vaccine." I
made no such claim, and debate over motivations only serves to sidetrack
this discussion. Rather, I referenced flu shot campaign literature which shows
that current statistics are being leveraged to increase flu
vaccination.[8]
There has been much discussion regarding the question of whether population
figures support the CDC's increases in flu-associated death estimates. The
CDC's "Influenza Model" (shown in Table 2 in their paper[9])
estimated an average of 18,715 annual flu-associated deaths occurred during the
1980s. (This figure supports the previous official estimate of
20,000.[10]) For the 1990s, their model estimated 35,271 annual
deaths. Thompson et al. state that the 65+ population increased 64% and 85+
population has "more than doubled" from 1972 to 1999 and "can indeed explain,
in part, why influenza-associated deaths have increased." However, it is only
logical to compare rising flu-associated mortality estimates with population
data over the same time period--the 1980s to 1990s. Here, without further,
model-independent ways to ascertain and verify the risk of flu-associated death
across all age groups, it remains undetermined and implausible that the
population increases are sufficient to explain the 88% rise in CDC estimates.
(See table.)
Table: Yearly averages over the 1980s and 1990s.
1980s
1990s
Percent
change
flu-associated deaths, all ages[9]
(ICD9 487, ICD10 J10-J11)
Thompson et al. ask for dialogue "on how best to refine these [CDC] estimates."
One suggestion would be to correct the widespread misrepresentation of
statistical estimates of flu-associated mortality as recorded flu deaths. In
their letter, German officials voiced the need to "always use correct
terminology",[5] and I think much can be gained from this advice. A
second suggestion would be to make clear to the public the assumptions built
into the CDC model, as well as the dangers such assumptions portend. For
example, the basic assumption that influenza is responsible for the majority of
seasonal excess deaths is controversial,[13] and weekly regression
analyses, as Simonsen et al. pointed out, "are in danger of being confounded by
other seasonal factors."[14]
I think discussion would be best served by focusing attention back to the
questions regarding the statistical inconsistencies in official flu-associated
mortality estimates.
Peter Doshi
References:
Competing interests:
None declared
Competing interests: No competing interests