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Health warnings on Australian tobacco products have been mandated
through federal legislation since 1973, being updated in 1987 and
1995. Issue of the current warnings followed a detailed study
examining the likely impact of prototypes, particularly on
youth.1 The warnings address
general health ("Smoking kills"), lung cancer, heart
disease, addiction, low infant birthweight, and harm to others
through passive smoking.
The adoption of health warnings was vigorously opposed by the tobacco
industry, whose internal research indicated that many smokers
disliked their prominence and more detailed content.2
Internationally, the track record of the tobacco
industry has been to oppose more "hard-hitting", specific warnings
in favour of blander, more general warnings such as "Smoking
reduces your fitness". We propose a new "hard-hitting"
cigarette pack warning.
Recent population-based cross-sectional data from four
countries3-6 including
Australia,7 together with data from two
large cohort studies,8,9 have consistently
identified smoking as the strongest environmental risk factor for
age-related macular degeneration (AMD), the leading cause of
blindness in Australia.10,11 All of these studies
have shown that people who currently smoke are two to five times more
likely to develop AMD than non-smokers or past smokers, and several
have demonstrated a dose-response relationship with pack-years of
smoking,6,8,9 and a decreased risk
with longer duration since cessation.4 Evidence of a gradient
between amount smoked and AMD severity has also been
shown.4,7
Based on data from two large population-based Australian
studies,12,13 there are currently
around 34 500 Australians aged over 50 years with legal blindness (ie,
they qualify for blind pension benefits because visual acuity in both
eyes is reduced to < 6/60). In over 80% of these people, blindness is
due to AMD.12 Two late stage AMD lesions
causing visual loss have been defined: "neovascular AMD",
characterised by macular haemorrhage and scarring (responsible for
two-thirds of cases), and "geographic atrophy", an atrophic macular
lesion which accounts for the remaining third.11 Increasing
age is the strongest risk factor for AMD, with the prevalence of late
stage lesions rising from under 1% in people aged less than 70 years to
over 10% in over-80-year- olds and more than one third in
over-90-year-olds.12
To date, longitudinal data relating smoking to the incidence of AMD
are less conclusive than cross-sectional population-based
studies. Both the Nurses' Health Study8 and the Physicians' Health
Study,9 however, relied on
self-reported diagnosis of AMD. The Macular Photocoagulation Study
report14 did not find an
association between a history of current smoking at the start of the
trial and incidence of AMD, but there may have been selection bias in
the recruitment of patients to a laser treatment trial.
Follow-up examinations have now been performed in three of the four
population-based cohorts3,4,7 to assess risk factors
for AMD. Of these, the Beaver Dam Eye Study is the only cohort yet to
report incidence data.15 This study found that, in
both men and women, smoking was related to the incidence of large
drusen, the principal precursor lesion for late stage AMD
lesions.16 Individually, each of the
three studies has relatively low statistical power to examine risk
factors for incident late stage AMD lesions, so that pooling of data
may be useful. Despite the present lack of firm incidence data, all of
the recent cross-sectional studies show a consistency of findings
that is difficult to ignore.
We estimate that there are currently almost 100 000 people with late
stage AMD in Australia, of which around 20 000 may have AMD directly
attributable to smoking. Further, we estimate that there are
currently more than 8200 Australians whose blindness from late stage
AMD can be attributed to smoking. These estimates, shown in the Table,
are based on Australian data collected in the Blue Mountains Eye
Study. Population-attributable risk estimates were derived from
odds ratios adjusted for age and sex.7 We repeated the
calculations using risk ratios from the Beaver Dam and Rotterdam
studies,3,4 and these separately
provided evidence that around 10 000 Australians are currently
likely to be blind as a result of smoking.
As our population ages, the prevalence of AMD and age-related
blindness will increase. At present, the only preventable confirmed
risk factor for AMD is smoking. We estimate that smoking may now be
responsible for around 20% of all cases of blindness in Australians
over the age of 50 years. As 80%-90% of blindness in Australia occurs in
those over 50 years, there is a similar overall proportion of people
blind as a result of smoking.
Most Australian smokers are aware that smoking is harmful to health.
However, knowledge of the role of smoking in causing many specific
diseases is unacceptably low. For example, a Victorian study found
that the percentage of smokers able (unprompted) to nominate
specific conditions linked to smoking was 54% (lung cancer), 38%
(emphysema), 38% (heart attack), 20% (unspecified cancer), 17%
(asthma), and 22% (bronchitis/respiratory problems).17
While research has shown dramatic increases in recognition of
cigarette pack warnings, only 66% of Australian smokers say that they
"at least sometimes notice" the current warnings.18 There is
clearly room for improvement.
Pack warnings that are novel and targeted at the concerns of specific
population subgroups are likely to have greater impact than blander,
older and more general warnings.19 As further
epidemiological evidence becomes available on the role of smoking in
causing specific diseases, it is important that this is reflected in
public information campaigns and warnings. For example, on 5
November 1998, the Thai government required "Smoking causes
impotence" to be included among the mandated warnings appearing
on cigarette packs.
There is no treatment for the majority of AMD cases, and support
services for blind people are very costly. The eyes are popularly
venerated as "mirrors to the soul" and blindness is greatly feared.
Everyone can imagine what it would be like to be blind. If "Smoking
is a major cause of blindness" were added to the current
Australian set of health warnings, some smokers might reconsider
their continued tobacco use.
Paul Mitchell
Associate Professor, Department of Ophthalmology
University of
Sydney, Sydney, NSW
Simon Chapman
Associate Professor
Department of Public Health and Community
Medicine
University of Sydney, Sydney, NSW
Wayne Smith
Senior Research Fellow
National Centre for Epidemiology and
Population Health
Australian National University, Canberra,
ACT
Email: paulmiATwestmed.wh.su.edu.au
Acknowledgement: The Blue Mountains Eye Study was supported by
the National Health and Medical Research Council and the Save Sight
Institute, University of Sydney
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Klein R, Klein BE, Linton KL, DeMets DL. The Beaver Dam Eye Study: the
relation of age-related maculopathy to smoking. Am J
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Vingerling JR, Hofman A, Grobbee DE, de Jong PT. Age-related
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Christen WG, Manson JE, Seddon JM, et al. A prospective study of
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Cooper RL. Blind registrations in Western Australia: a five year
study. Aust N Z J Ophthalmol 1989; 107: 875-879.
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Mitchell P, Smith W, Attebo K, Wang JJ. Prevalence of age-related
maculopathy in Australia. The Blue Mountains Eye Study.
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Attebo K, Mitchell P, Smith W. Visual acuity and the causes of
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Taylor HR, Livingston PM, Stanislavsky YL, McCarty CA. Visual
impairment in Australia: distance visual acuity, near vision, and
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Am J Ophthalmol 1997; 123: 328-337.
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Macular Photocoagulation Study Group. Risk factors for
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to age-related macular degeneration. Arch Ophthalmol 1997;
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Klein R, Klein BE, Moss SE. Relation of smoking to the incidence of
age-related maculopathy. The Beaver Dam Eye Study. Am J
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Klein R, Klein BE, Jensen SC, Meuer SM. The five-year incidence and
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household surveys. Quit Evaluation Studies Number 8, 1994-1995.
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Reprints: Professor P Mitchell, Department of Ophthalmology,
University of Sydney, Hawkesbury Road, Westmead, NSW 2145.
©MJA 1999
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