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Philip Morris

Environmental Tobacco Smoke and Heart Disease

Date: 05 Aug 1993
Length: 647 pages
2023511661-2023512307
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Author
S, W.L.
Named Person
Adena, M.A.
Alderson, M.R.
Alexander, H.M.
Armitage, A.
Arnold, J.
Aronow
Aronow, W.S.
Aviado, D.
Bansal, A.K.
Barrettconnor, E.
Bernheim, J.
Bertanelli, F.
Bodurtha, J.N.
Bossano, R.
Buerger
Burghuber, O.C.
Butler
Butler, T.
Caldwell, Ads
Casper, M.
Chamberlain, J.
Chee, E.
Chopra, C.
Clarke, W.
Comstock, G.W.
Correa, P.
Crepat, J.
Criqui, M.
Criqui, M.H.
Croft, J.
Davis
Davis, J.W.
Dobson, A.J.
Donnan, G.A.
Doyle, A.E.
Eckfeldt, J.
Etzel, R.A.
Evans, G.
Fabiano, P.
Feldman, J.
Filippelli, M.
Fortmann, S.P.
Froeb, H.F.
Garland, C.
Gerber, A.
Gillis, C.R.
Glantz, S.A.
Green
Green, J.
Green, M.S.
Haber, P.
Hames, C.G.
Harari, G.
Hawthorne, V.M.
He, Y.
Heiss, G.
Heller, R.F.
Helsing, K.J.
Hewitt, J.K.
Hicks, L.L.
Hirayama, T.
Hole, D.J.
Hollarbush, J.
Howard, G.
Humble
Humble, C.
Hunt, S.C.
Isenberg, W.M.
Jacobson, M.S.
Kawachi
Kefalides, A.
Khalfen, E.S.
Klochkov, V.A.
Kristensen
Kulik, J.A.
Kuller, L.H.
Lauer, R.
Lee, P.N.
Leone
Leone, A.
Lilienfield, D.E.
Lloyd, D.M.
Martin
Martin, M.J.
Matsumoto, T.
Matsushita
Matsushita, M.
Mcmurray
Mcmurray, R.G.
Mcneil, J.J.
Mennear, J.
Mizell, M.
Mori, L.
Moskowitz, W.B.
Mosteller, M.
Munby, J.
Neill, G.C.
Nussbaum, M.
Ockene, J.K.
Omalley, H.M.
Palmer
Palmer, J.R.
Parmley, W.W.
Pomrehn, P.
Punzengruber, C.
Rosenberg, L.
Sandler, D.P.
Schieken, R.M.
Segrest, J.P.
Shaham, J.
Shapiro, S.
Shelton, L.
Shenkder, I.R.
Shionoya, S.
Sievers, R.E.
Silberbauer, K.
Singh, C.B.
Sinsheimer, P.J.
Sinzinger, H.
Soni, G.L.
Spierto, F.W.
Steenland, K.
Suarez, L.
Sun, Y.P.
Surgeon General
Svendsen
Svendsen, K.H.
Szklo, M.
Taylor
Tell, G.
Thompson, D.L.
Tribble, D.L.
Tyroler, H.A.
Virgolini, I.
Watanabe, I.S.
Weetman, D.F.
Wells, A.J.
Wexler, L.
Whig, J.
White, J.R.
Williams, R.R.
Wingard, D.L.
Zhu
Zhu, B.Q.
Type
REPT, REPORT, OTHER
BIBL, BIBLIOGRAPHY
Site
R529
Document File
2023511660/2023512308/Ets: Heart Disease 930900
Characteristic
PARE, PARENT
Master ID
2023511661/2307
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Area
SCIENTIFIC AFFAIRS/BLACK LATERAL OLD S&T
Named Organization
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American Heart Assn
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Chest
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Lancet
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Mcgill Univ
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Nas, Natl Academy of Sciences
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Verlag Chemie Intl
Who, World Health Org
Wiener Klinische Wochenschrift
Litigation
Okag/Privilege Withdrawn
Okag/Produced
Date Loaded
24 May 1999
UCSF Legacy ID
sgc02a00

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} 5. Failure to control adequately for biases stemming from potential confounding!variables. 6. Failure to confirm causes of death via autopsy or other histological methods. Reviews claiming ETS-associated risk ("unfavorable" reviews) Despite the scientific weaknesses in the epidemiologic literature on ETS and heart disease, several recent reviews have concluded that ETS is associated with an increased risk of heart disease and that, in~fact, such exposure causes a large number of deaths each year. Each of these reviews attempted to estimate an overall risk based on the combined data from the epidemiologic studies. These estimated risk ratios are provided in the following table. 8
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Epidemiological data have also been reported for ETS exposure in~relation to Buerger's disease. Buerger's disease is an inflammatory condition leading to arterial occl~usion in the peripheral vascular system. It has been, reported to be statistically associated with cigarette smoking. Matsushita, et al.14 studied 40 Buerger's disease patients, in relation to smoking history and history of ETS exposure. Based on an examination of the progression or "aggravation" of the disease in these patients, the authors concluded that their results confirmed'the relationship of "active" smoking: with Buerger's disease, but that the "effects of passive smoking on the disease process were still inconclusive." A list of the most common weaknesses in, the epidemiological literature on ETS and cardiovascular disease is provided below. It will be recognized that these are characteristic of epidemiological studies of ETS in, general, not simply those relating to heart and other cardiovascular diseases. 1. Small sample sizes. 2. Lack of statistical significance, or failure to test for statistical significance. 3. Potential misclassification of the smoking status of study participants. 4. Inadequate assessment of ETS exposure. - 7 -
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Only five of the 12 epidemiological studies regarding ETS and heart disease report a statistically significant result at the 95% level of confidence. These are: (1) He, et al. (1989), a Chinese language report based on only 34 female heart disease patients; (2) Helsing, et al. (1988), a study based~ on a Maryland census in which~the information~regarding spousal smoking (used to estimate ETS exposure) was from 1963; (3) Hole, et al. (1989), a Scottish study based on only 84 heart disease deaths; (4) Martin, et al. (1988), a report based on only 23 women who reported having a heart attack and which was given at a conference but apparently not otherwise accepted for publication; and (5) Dobson, et al. (1991), an Australian study which reported an association with home exposure for women only and not at all for workplace exposure. In sum, seven of the 12 studies of ETS exposure and heart disease have failed to report a statistically significant association. In the five studies that have claimed a statistically significant relationship, three were from outside the United States. Three were very small-scale. All of these studies suffer from a variety of serious methodological weaknesses. In addition to the 12 ETS/heart disease reports, there is also an epidemiological (case-control) study reporting that spousal smoking was associated with increased stroke risk [relative risk of 1.7 (95% CI: 1.1-2.6)],13 - 6 -
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cardiovascular diseases and the work environment. Thus, the major reviews were those by Wells in 1988, by Glantz and Parmley in 1991 and by Steenland in 1992. These three reports are discussed further below. A. Judson Wells, a consultant to the American Lung Association, statistically combined the data from several reports on ETS and heart disease, including both prospective (cohort)i and case-control studies. He then calculated overall relative risks (ETS exposed versus nonexposed) for lung cancer (1.44 for females;. 2.1 for males)!, cancers other than lung (1.16 for females; no risk elevation for males) and heart disease (1.23 for females; 1.31 for males). Using, various assumptions and statistical manipulations, Wells calculated' numbers of ETS-related deaths for each disease category. He claimed that ETS exposure resulted in 46,000 deaths per year in nonsmokers. Of these, 3,000 are claimed to be fromi lung, cancer. For cancers other than the lung, he calculated that ETS exposure results in 11,0001annual deaths. The largest number of deaths from ETS exposure was claimed to be due to heart disease. He claimed that 32,000 nonsmoker heart disease deaths per year stemifrom ETS exposure. A more widely publicized review of ETS and heart disease was undertaken by two authors from the Department of Medicine, University of California, San Francisco. In their 1991 paper, - 10 -
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Stanton Glantz and William Parmley conclude that ETS exposure is statistically associated~ with an estimated 30% increase (relative risk of 1.3) in heart disease risk in nonsmokers. They argue, relying on~ Wells, that this translates into 37, 000 heart disease deaths in nonsmokers stemming from ETS exposure. Glantz and Parmley also discuss a number of biochemical and experimental studies which purportedly support the biological plausibility of such a relationship. In evaluating the claims by Wells and by GLantz and Parmley, it should'be emphasized that meta-analysis, the technique from which they derive their risk estimates, is appropriately used only when the underlying studies are highly similar and of high quality. If the underlying studies are based~ on different populations and~ procedures and suffer from serious methodological weaknesses, then~any meta-analysis will consequently be invalidated. These considerations are directly applicable to an evaluation of risk claims regarding ETS and~ heart disease. Wells (1988)~ and: Glantz and Parmley (1991) base their claims on meta-analyses of a small group of, epidemiological studies reporting a relationship between ETS exposure and an increased~ risk of heart disease. In general, these studies deal with spousal smoking and assess heart disease risk in the nonsmoking spouse. Otherwise, these studies used widely disparate methodologies, study populations and endpoints. Several are very weak, preliminary, available only in. - 11 -
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similar to that reported by Wells and'by Glantz and Parmley. This estimation process involved: positing an overall increase in relative risk of heart disease associated with ETS exposure; making adjustments for potential misclassification and for background exposure; estimating the extent of exposure to ETS; and estimating the fraction of nonsmoker heart disease deaths attributable to ETS exposure. These estimates were incorporated into a formula using data on U.S. heart disease death rates and population estimates, from which~was derived an estimated number of annual heart disease deaths attributed to ETS exposure. According to Steenland's calculations, "the overall estimate of ETS-attributable heart disease deaths for never-smokers and former smokers is 35000 to 40000." He further commented that these increased risks of death "are higher than those accepted in regulating environmental toxins." In a 1992 position statement from the American, Heart Association,, it was concluded that ETS causes heart disease. (Taylor, et al.)20 Reviews emphasizing inconclusiveness of the data ("favorable" reviews) Reviews such as those by Wells, by Glantz and Parmliey and by Steenland often receive a great deal of publicity. However, it is important to recognize that there have been, a number of other - 13 -
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abstract form, or are based on such scanty data that they quite arguably are not sufficiently reliable or valid considered seriously in a meta-analysis. even to be Kyle Steenland, a National•Institute for Occupational Safety and Health employee, also performed a risk assessment of ETS and heart disease. In a 1992 paper, he calculated that 35,000- 40,000 annual U.S. heart disease deaths are attributable to ETS exposure. He concluded that "heart disease mortality is contributing the bulk of the public health burden imposed by passive smoking." There were two important differences between Steenland's estimation process and that used by Wells, and later adopted by Glantz and Parmley. First, Steenland did not do a meta-analysis to obtain~ a pooled estimate of relative risk for heart disease mortality associated'with ETS exposure. Instead~, he simply adopted~ the relative risk reported in a single study of a Maryland~ sample (Helsing, et al., 1988; see endnote ref. 5) and applied~ that to the entire U.S. population. Second~, he focused only on~ heart disease and did not attempt to calculate ETS-related deaths from other diseases. Other than the above, Stteenland'.'s procedure for calculating deaths attributable to ETS exposure was generally - 12 -
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are instigated, and some objective measure of degree of exposure can be devised. (p. 215)24 c. D.F. Weetman presented a similar conclusion at an indoor air quality conference in~Bangkok, Thailand in November 1991. It is concluded that too many important potentially confounding, factors have been~ overlooked to decide if there is an association between exposure to ETS and cardiovascular diseases. (p. 275)25' d. Another scientific review of this literature was performed! by two physicians from the University of Munich, Germany and given at an international conference in Hungary in June 1990. The conclusion was similar.. Taking into account the small increase in coronary risk in passive smokers as compared to non-exposed subjects and also the low validity and small number of epidemiological studies available and the fact that their results are at least inconsistent, a relationship between passive smoking and cardiovascular diseases cannot be established on these data. (p. 6)26 e. In a 1991 book discussing a wide range of issues involving ETS, the literature on heart disease was reviewed by Alan Armitage, former director of toxicology of a major European research laboratory and head of pharmacology at the - 16 -
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scientists have undertaken more balanced and' critical reviews of the more recent data and have j'udged that it remains inconclusive. Several of the most significant of these recent reviews, and their conclusions, are as follows. a. At a major conference on ETS held~ at McGill University in 1989,, Lawrence Wexler, of the New York Medical College, concluded that recent data did not provide a basis for altering the earlier conclusions by the Surgeon General and National Research Council concerning ETS and cardiovascular disease. Based on the available evidence, it is this author's opinion that it has not been demonstrated that exposure to ETS increases the risk of cardiovascular disease. (p. 139)23 b. A similar evaluation was made by two scientists, D.F. Weetman and J. Munby, from the School of Pharmacology,. Sunderland Polytechnic, Sunderland, United Kingdom. They presented their conclusions fr= a review of the literature on ETS and heart disease at an international conference on i_ndoor air quality held'. in Lisbon, Portugal in April 1990. It is concluded that no increased risk of cardiovascular disease can be associated unequivocally with exposure to ETS, and it seems probable that this will continue to be the case until specifically designed trials - 15 -
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Tobacco Research Council Laboratories in the United Kingdom. He judged that the scientific data have not established an increased heart disease risk in nonsmokers exposed to ETS. It is clear that the evidence for a harmful effect of ETS in~enhancing CHD [Icoronary heart disease) risk in non,smokers is not very convincing. . . . (p. 114)27 f. In a subsequent review in 1993, Armitage, writing as a consultant pharmacologist and toxicologist, expressed a similar evaluation of the ETS/heart disease literature. On the current evidence a causal relationship between exposure.to ETS and the development of CHD has not been proved. (p. 27)28 g. Armitage's 1993 review appeared in the Journal of Smoking-Related Diseases. In an~editorial in the same journal issue, A.D.S. Caldwell, the journal's managing editor, emphasized that the issue of confounding variables was of particular importance in the case of heart disease. This is because of the hundreds of factors reportedly associated with the disease. Caldwell observed that the numerous heart disease N risk factors make it extremely difficult to make confident ~ CJ statements about a potential role of ETS. N W - 17 -

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