Has risk associated with smoking increased? Results from the Copenhagen Center for Prospective Population Studies (original) (raw)
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Differences between studies in reported relative risks associated with smoking: An overview
Public Health Reports
REPORTED RELATIVE RISKS associated with smoking differ between studies; these differences may reflect true biological differences between populations or may be research artifacts introduced by differences in factors such as amount smoked or smoking duration. The authors reviewed the literature published before June 1-992 on relative risks associated with smoking for heart disease, stroke, lung cancer, and chronic obstructive lung disease. They quantified the effect of variables such as age, amount smoked, and smoking duration on reported relative risks. The main reasons for the variation in reported relative risks were: misclassification of former smokers as never smokers, the use of mortality rate ratios rather than incidence rate ratios, a possible period effect suggesting increasing relative risks over time, and differences in the amount smoked. It is far more likely that these factors are responsible for the observed variation between studies than that the variations reflect true biological differences between populations. Using relative risks from other studies is therefore justified in calculating a population attributable risk if the studies are carefully selected and address factors such as amount smoked and period effects.
BMJ open, 2017
There is a shift in the smoking population from daily smokers to light or occasional smokers. The knowledge about possible adverse health effects of this new smoking pattern is limited. We investigated smoking habits with focus on occasional smoking in relation to total mortality in a follow-up study of a Norwegian general population. A population study in Tromsø, Norway. We collected smoking habits and relevant risk factors in 4020 women and 3033 men aged 30-89 years in the Tromsø Study in 2001. The subjects were followed up regarding total mortality through June 2015. Among the participants, there were 7% occasional smokers. Occasional smokers were younger, more educated and used alcohol more frequently than other participants. A total of 766 women and 882 men died during the follow-up. After the adjustment for confounders, we found that occasional smoking significantly increased mortality by 38% (95% CI 8% to 76%) compared with never smokers. We report a dose-response relationshi...
Excess mortality among cigarette smokers: changes in a 20-year interval
American Journal of Public Health, 1995
OBJECTIVES: This study was undertaken to examine changes in smoking-specific death rates from the 1960s to the 1980s. METHODS: In two prospective studies, one from 1959 to 1965 and the other from 1982 to 1988, death rates from lung cancer, coronary heart disease, and other major smoking-related diseases were measured among more than 200,000 current smokers and 480,000 lifelong non-smokers in each study. RESULTS: From the first to the second study, lung cancer death rates (per 100,000) among current cigarette smokers increased from 26 to 155 in women and from 187 to 341 in men; the increase persisted after current daily cigarette consumption and years of smoking were controlled for. Rates among nonsmokers were stable. In contrast, coronary heart disease and stroke death rates decreased by more than 50% in both smokers and nonsmokers. The all-cause rate difference between smokers and nonsmokers doubled for women but was stable for men. CONCLUSIONS: Premature mortality (the difference ...
American Journal of Epidemiology, 2002
The authors investigated the association between changes in smoking habits and mortality by pooling data from three large cohort studies conducted in Copenhagen, Denmark. The study included a total of 19,732 persons who had been examined between 1967 and 1988, with reexaminations at 5- to 10-year intervals and a mean follow-up of 15.5 years. Date of death and cause of death were obtained by record linkage with nationwide registers. By means of Cox proportional hazards models, heavy smokers (>or=15 cigarettes/day) who reduced their daily tobacco intake by at least 50% without quitting between the first two examinations and participants who quit smoking were compared with persons who continued to smoke heavily. After exclusion of deaths occurring in the first 2 years of follow-up, the authors found the following adjusted hazard ratios for subjects who reduced their smoking: for cardiovascular diseases, hazard ratio (HR) = 1.01 (95% confidence interval (CI): 0.76, 1.35); for respiratory diseases, HR = 1.20 (95% CI: 0.70, 2.07); for tobacco-related cancers, HR = 0.91 (95% CI: 0.63, 1.31); and for all-cause mortality, HR = 1.02 (95% CI: 0.89, 1.17). In subjects who stopped smoking, most estimates were significantly lower than the heavy smokers'. These results suggest that smoking reduction is not associated with a decrease in mortality from tobacco-related diseases. The data confirm that smoking cessation reduces mortality risk.
Scandinavian journal of public health, 2014
In the 1990s, several studies noted a large gap in life expectancy between Western and Eastern European countries. It was speculated that this could be explained by environmental pollution, socioeconomic factors, lifestyle and psychosocial stress. A weakness in addressing the issue has been the lack of prospective studies with mortality as end point. We used the national population registries (between 1996 and 1998) to screen a cohort of 269 55-year-old subjects in Sweden and Estonia. We assessed conventional risk factors, lifestyle and socio-economic factors. A 13-year follow-up regarding all-cause and cardiovascular mortality was done. Smoking and, to a lesser extent, plasma levels of interleukin-6 were significant predictors for CVD and non-CVD mortality in men, but none of the other conventional risk factors reached statistical significance. During the follow-up period, 22 of the 52 male smokers died compared to 8 of the 85 male non-smokers (p<0.01). Ten of the smokers died o...
BMJ open, 2014
Providing lifetime smoking prevalence data and gender-specific cigarette consumption data for use in epidemiological studies of tobacco-induced cancer in Norway. Characterising smoking patterns in birth cohorts is essential for evaluating the impact of tobacco control interventions and predicting smoking-related mortality. Norway. Previously analysed annual surveys of smoking habits from 1954 to 1992, and individual lifetime smoking histories collected in 1965 from a sample of people born in 1893-1927, were supplemented with new annual surveys of smoking habits from 1993 to 2013. Age range 15-74 years. Current smoking proportions in 5-year gender-and-birth cohorts of people born between 1890 and 1994. The proportion of smokers increased in male cohorts until the 1950s, when the highest proportion of male smokers (76-78%) was observed among those born in 1915-1934. Among women, the peak (52%) occurred 20 years later, in women born in 1940-1949. After 1970 smoking has declined in all ...
Tobacco Control, 2007
Study objective: To study the effect of long-term smoking on all-cause and cause-specific mortality, and to estimate the effects of cigarette and cigar or pipe smoking on life expectancy. Design: A long-term prospective cohort study. Setting: Zutphen, The Netherlands. Participants: 1373 men from the Zutphen Study, born between 1900 and 1920 and studied between 1960 and 2000. Measurements: Hazard ratios for the type of smoking, amount and duration of cigarette smoking, obtained from a time-dependent Cox regression model. Absolute health effects of smoking are expressed as differences in life expectancy and the number of disease-free years of life. Main results: Duration of cigarette smoking was strongly associated with mortality from cardiovascular disease, lung cancer and chronic obstructive pulmonary disease, whereas both the number of cigarettes smoked as well as duration of cigarette smoking were strongly associated with all-cause mortality. Average cigarette smoking reduced the total life expectancy by 6.8 years, whereas heavy cigarette smoking reduced the total life expectancy by 8.8 years. The number of total life-years lost due to cigar or pipe smoking was 4.7 years. Moreover, cigarette smoking reduced the number of disease-free life-years by 5.8 years, and cigar or pipe smoking by 5.2 years. Stopping cigarette smoking at age 40 increased the life expectancy by 4.6 years, while the number of disease-free life-years was increased by 3.0 years. Conclusions: Cigar or pipe smoking reduces life expectancy to a lesser extent than cigarette smoking. Both the number of cigarettes smoked and duration of smoking are strongly associated with mortality risk and the number of life-years lost. Stopping smoking after age 40 has major health benefits. S moking has been recognised as a health hazard for many years. Smoking causes a wide range of diseases, including cancer, chronic obstructive pulmonary disease (COPD) and cardiovascular diseases (CVD), and smoking cessation has impressive health benefits. 1-3 Cigarette smoking cessation decreases the risk of diseases and also increases life expectancy. Even stopping at age 60 gains about 3 years of life expectancy. Much less is known about the adverse effects of long-term cigar or pipe smoking. Smoking has both long-and short-term effects. As smoking habits change during life, information on long-term smoking history is required to obtain correct estimates of the long-term health effects of smoking. Because in most studies the level of detail on smoking history is limited, the impact of various aspects of the smoking history remains unclear. Leffondré et al 8 show the importance of information on smoking duration, intensity and time since cessation in this respect. Although smoking duration has been associated with mortality before, most studies focused on cancer mortality rather than on CVD and COPD mortality. In epidemiological studies, hazard ratios are commonly used to express the impact on mortality. Hazard ratios express effects for one exposure group relative to the effect of the unexposed group-that is, the reference group-but do not give information regarding absolute public health effects. Therefore, life expectancies should be calculated. Although concepts like life expectancy are more informative and readily grasped by all, they are not reported frequently.
The role of smoking in changes in the survival curve: an empirical study in 10 European countries
Annals of epidemiology, 2015
We examined the role of smoking in the two dimensions behind the time trends in adult mortality in European countries, that is, rectangularization of the survival curve (mortality compression) and longevity extension (increase in the age-at-death). Using data on national sex-specific populations aged 50 years and older from Denmark, Finland, France, West Germany, Italy, the Netherlands, Norway, Sweden, Switzerland, and the United Kingdom, we studied trends in life expectancy, rectangularity, and longevity from 1950 to 2009 for both all-cause and nonsmoking-related mortality and correlated them with trends in lifetime smoking prevalence. For all-cause mortality, rectangularization accelerated around 1980 among men in all the countries studied, and more recently among women in Denmark and the United Kingdom. Trends in lifetime smoking prevalence correlated negatively with both rectangularization and longevity extension, but more negatively with rectangularization. For nonsmoking-relat...
Re:" Modeling smoking history: A comparison of different approaches"-Reply
The impact of cigarette smoking on various diseases is studied frequently in epidemiology. However, there is no consensus on how to model different aspects of smoking history. The aim of this investigation was to elucidate the impact of several decisions that must be made when modeling smoking variables. The authors used data on lung cancer from a case-control study undertaken in Montreal, Quebec, Canada, in 1979. The roles of smoking status, intensity, duration, cigarette-years, age at initiation, and time since cessation were investigated using time-dependent variables in an adaptation of Cox's model to case-control data. The authors reached four conclusions. 1) The estimated hazard ratios for current and ex-smokers depend strongly on how long subjects are required to not have smoked to be considered "ex-smokers." 2) When the aim is to estimate the effect of continuous smoking variables, a simple approach can be used (and is proposed) to separate the qualitative difference between never and ever smokers from the quantitative effect of smoking. 3) Using intensity and duration as separate variables may lead to a better model fit than using their product (cigarette-years). 4) When estimating the effects of time since cessation or age at initiation, it is still useful to use cigarette-years, because it reduces multicollinearity. Downloaded from 816 Leffondré et al. Am J Epidemiol 2002;156:813-823 by guest on July 3, 2015 http://aje.oxfordjournals.org/ Downloaded from 820 Leffondré et al. Am J Epidemiol 2002;156:813-823