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Objectives: A four-stage model of the cigarette epidemic was proposed in 1994 to communicate the long delay between the widespread uptake of cigarette smoking and its full effects on mortality, as had been experienced in economically developed countries where cigarette smoking became entrenched decades earlier in men than in women. In the present work, the question of whether qualitative predictions from the model have matched recent trends in smoking and deaths from smoking in countries at various levels of economic development is assessed, and possible projections to the year 2025 are considered., Methods: The proportion of all deaths attributed to tobacco was estimated indirectly for 41 high-resource and medium-resource countries from 1950 to the most recent year for which data were available, generally about 2005-2009. The trends in tobacco-attributed mortality in later middle age were then projected forward to 2025, based on recent trends in tobacco-attributed mortality in early middle age., Results: In developed countries the prevalence of smoking has continued to decrease in both sexes, although the rate of decrease has slowed and is less than that predicted by the original version of the model. Over the past 20 years the proportionate contribution of smoking to all deaths has decreased in men while continuing to increase or plateau among women. Although the proportion of all deaths at ages 35-69 that are attributed to smoking is still generally greater in men than in women, the male and female proportions are converging and will probably cross over in some high resource countries. Projections through to 2025 suggest that male and female smoking prevalence and smoking-attributed mortality will decrease in parallel in most developed countries towards lower limits that are not yet defined. In developing countries the model seems generally applicable to men but cannot predict whether or when women will begin smoking in large numbers. Modified criteria that describe the stages of the epidemic separately for men and women would be more generalisable to developing countries., Conclusions: The four-stage model of the cigarette epidemic still provides a reasonably useful description in many developed countries. Its relevance to developing countries could be improved by describing the stages of the epidemic separately for men and women.

Cigarettes with lower machine measured "tar" and nicotine yields have been marketed as "safer" than high tar products over the last four decades, but there is conflicting evidence about the impact of these products on the disease burden caused by smoking. This paper critically examines the epidemiological evidence relevant to the health consequences of "reduced yield" cigarettes. Some epidemiological studies have found attenuated risk of lung cancer but not other diseases, among people who smoke "reduced yield" cigarettes compared to smokers of unfiltered, high yield products. These studies probably overestimate the magnitude of any association with lung cancer by over adjusting for the number of cigarettes smoked per day (one aspect of compensatory smoking), and by not fully considering other differences between smokers of "high yield" and "low yield" cigarettes. Selected cohort studies in the USA and UK show that lung cancer risk continued to increase among older smokers from the 1950s to the 1980s, despite the widespread adoption of lower yield cigarettes. The change to filter tip products did not prevent a progressive increase in lung cancer risk among male smokers who began smoking during and after the second world war compared to the first world war era smokers. National trends in vital statistics data show declining lung cancer death rates in young adults, especially males, in many countries, but the extent to which this is attributable to "reduced yield" cigarettes remains unclear. No studies have adequately assessed whether health claims used to market "reduced yield" cigarettes delay cessation among smokers who might otherwise quit, or increase initiation among non-smokers. There is no convincing evidence that past changes in cigarette design have resulted in an important health benefit to either smokers or the whole population. Tobacco control policies should not allow changes in cigarette design to subvert or distract from interventions proven to reduce the prevalence, intensity, and duration of smoking.