Characteristics of current smokers,former smokers,and second-hand exposure and evolution between 1985 and 2007

Abstract

Aims

The aim of this study was to assess trends in the prevalence of adult smoking habits between 1985–1987 and 2005–2007 in three distinct areas of France and their contribution to coronary heart disease (CHD) death rates.

Methods

Participants were recruited as part of the French Monitoring trends and determinants in Cardiovascular disease survey in 1985–1987 (n = 3760), 1995–1997 (n = 3347), and 2005–2007 (n = 3573). They were randomly selected from electoral rolls after stratification for sex, 10-year age group (35–64 years), and town size. Smoking habits were analyzed by questioning the participants about earlier or current consumption, the number of cigarettes smoked per day, age at first cigarette, pipe tobacco and cigarillo consumption, quit attempts, age at quitting, and second-hand exposure. Predicted CHD death rates as a function of smoking were predicted with the SCORE risk equation.

Results

In men, a significant decrease in tobacco exposure (from 40 to 24.3%) between 1985–1987 and 2005–2007 was observed. In women, the prevalence of current smokers increased from 18.9 to 20% and that of former smokers rose from 8.7 to 25.5%. In both men and women, average daily cigarette consumption and second-hand exposure to smoke fell between 1995–1997 and 2005–2007. Predicted CHD death rates as a function of smoking trends decreased in men (range 10–15%) but increased in women (range 0.1–3.6%).

Conclusion

This study found divergent trends in the prevalence of smoking in men and women aged between 35 and 64 years over the period of 1985 to 2007. These changes may have contributed to the decline in CHD death in men but not in women.

Keywords

cardiovascular risk factors coronary heart disease passive smoking tobacco

Introduction

Smoking is the leading cause of preventable disease and is responsible for 66 000 cardiovascular deaths a year in France alone (10–12% of total mortality) [1–3]. Over recent decades, a number of antitobacco health promotion policies have been implemented, such as cancer action plans, smoke-free environment laws, health warnings, extension of advertising and sponsorship bans, and tax/price increases. However, it is essential to evaluate the efficacy of those campaigns.

In the last 20 years, the coronary heart disease (CHD) rate has decreased in the three areas of north, east and southwest France surveyed in the World Health Organization's Monitoring trends and determinants in Cardiovascular disease (MONICA) study [4]. Between 1997 and 2002, the favorable trend continued but slowed in women [5, 6]. These changes over time may be linked to differing trends in the prevalence of cardiovascular risk factors in men and women [7]. It is noteworthy that the prevalence of smoking in men has been high for the past 60 years and is now tending to fall, whereas women only started to smoke in large numbers much more recently [3].

Although improved management of acute forms of CHD can reduce recurrence, only the systematic prevention of risk factors will prevent new cases of CHD from occurring. Management of tobacco consumption is one of the most fundamental tools in CHD prevention. Since 1985, the MONICA teams have carried out several surveys of CHD risk factors in representative samples of the French populations [8]. This report presents the trends in the prevalence of tobacco exposure over 20 years and their relationship with cardiovascular death risk.

Methods

Population sample

Participants were recruited in the framework of the World Health Organization MONICA population survey [9–12] in 1985–1987 and 1995–1997, and in the MONA LISA survey in 2005–2007 [13]. Data were collected in three different geographical areas of France (Lille Urban Community in Northern France, the Bas-Rhin county in eastern France and the Haute-Garonne county in southern France), each of which comprises approximately 500 000 inhabitants aged between 35 and 64 years. Participants (aged 35–64 years in the MONICA surveys and 35–74 years in the MONA LISA survey) were selected randomly from electoral rolls after stratification by town size, sex and age to obtain 200 participants for each sex and each 10-year age group. The same sampling frame was used in all three surveys. Analyses were performed solely on participants aged 35–64 years: 3760 participants in the first survey (1985–1987), 3347 in the second survey (1995–1997) and 3573 in the third survey (2005–2007). The participation rates in the surveys were 69, 76 and 70% in Lille Urban Community, 66, 51 and 40% for the Bas-Rhin county and 58, 63 and 50.2% for the Haute-Garonne county in 1985–1987, 1995–1997 and 2005–2007, respectively. The study protocol was approved by the appropriate independent ethics committees.

Data collection

After giving their written informed consent, the participants' physical measurements were taken by a specially trained nurse. With the help of medical staff if required, the participants then completed a standard questionnaire on demographic variables, socioeconomic status and medical history (including medication use, smoking habits and alcohol consumption). A physical examination was performed in the morning and a fasting blood sample was drawn. The same methodology was used in all three centers.

In the three surveys, smoking status was addressed by questions on earlier or present consumption of cigarettes, cigars and pipe tobacco. The 1995–1997 and 2005–2007 surveys featured additional questions on age at first cigarette, age at quitting, number of quit attempts and second-hand smoke exposure. The latter exposure was assessed by one single question as follows: ‘On average, how many hours a day are you exposed to smoke from other persons?’ Exposure was assessed in never and former smokers only. Participants were categorized as never smokers, former smokers and current smokers (i.e. participants smoking at least one cigarette a day).

To estimate the contribution of tobacco exposure trends to CHD mortality changes between 1985–1987 and 2005–2007, we predicted the yearly CHD death risk as a function of smoking exposure with the low-risk country SCORE equation for men and women [14]: Yearly CHD death rate = [1-(S_age10/S_age)]/10. The age functions, S0 and S010, were taken from the low-risk country results in Conroy et al. [14]. For each participant we calculated the yearly CHD rate that was attributable to age and smoking exposure by setting cholesterol and systolic blood pressure to 6 mmol/l and 120 mmHg and smoking at 1/0 according to the participant's exposure to tobacco.

Statistical analysis

Means and percentages were estimated from survey data while taking account of the stratification and sampling design by age, sex and geographical area. Estimates were obtained by computing weighted averages of the individual stratum-specific estimates and pooling them across strata (with direct standardization against the 1996 population). Data were analyzed with a generalized linear model (for continuous variables) and logistic regression (for categorical variables), adjusted for age and center. Age group × survey or geographical area × survey interaction terms were used to test homogeneity of the results across age groups and geographical areas. A P value of less than 0.05 was considered to be statistically significant. All statistical analyses were performed with SAS(r) software (version 9.1; SAS Institute Inc., Cary, North Carolina, USA).

Results

Prevalence and trends

In men, there was a significant decrease in current tobacco consumption (from 40 to 24.3%, P < 0.0001) between 1985–1987 and 2005–2007 (Table 1). The prevalence of former smokers remained stable at around 37%, whereas the frequency of never smokers increased from 24.7 to 38.2%. These changes were homogeneous across all age groups (Fig. 1) and geographical areas (Fig. 2).

In women, the prevalence of current smokers increased slightly between 1985–1987 and 2005–2007 (from 18.9 to 20%, NS) and that of former smokers increased markedly (from 8.7 to 25.5%) (Table 1). Accordingly, the prevalence of never smokers decreased markedly from 72.4 to 54.6% over the same period. The increase in tobacco exposure (both earlier and current) started in 1995–1997 (especially in the 35–54 years age group) and was notably observed in the 45–64 years age group in 2005–2007 (Fig. 1). Among young women, however, the proportion of current smokers decreased between 1995–1997 and 2005–2007. These trends were homogeneous across geographical areas (Fig. 2).

Table 1

Age and center-adjusted prevalence and 95% confidence intervals of current smokers, former smokers, and never smokers in MONICA

	Men				Women
	1985-1987	1995-1997	2005-2007	P value	1985-1987	1995-1997	2005-2007	P value
n	1924	1692	1795		1836	1655	1778
Current smokers (%)	40.3 (38.1-42.5)	29.1 (26.9-31.3)	24.3 (22.3-26.3)	<0.0001	18.9 (17.1-20.7)	19.9 (18-21.8)	20.0 (18.1-21.9)	NS
Former smokers (%)	35.0 (32.8-37)	39.0 (36.7-41.3)	37.5 (35.3-39.7)		8.7 (7.4-10)	19.5 (17.6-21.4)	25.5 (23.5-27.5)
Never smokers (%)	24.7 (22.8-26.7)	31.9 (29.7-34.1)	38.2 (36-40.4)		72.4 (70.4-74.4)	60.6 (58.2-63)	54.6 (52.3-56.9)

Data were standardized on 1996 age distribution for each geographical area. NS, non-significant.

Predicted impact on CHD death

In men, the predicted CHD death rate decreased between 1985–1987 and 2005–2007 by approximately 10% in the 35–54 years age group and by 15% in the 55–64 years age group (Fig. 3). The decrease was more pronounced between 1985–1987 and 1995–1997 (range 7.2–9.5%) than between 1995–1997 and 2005–2007 (range 1.4–7.3%). In women, the predicted CHD death rate increased by 3.6% in the 45–54 years age group and hardly changed in the other age group (range 0.1–0.5%). A slight decrease was observed between 1985–1987 and 1995–1997 (range 0.7–1.5%), whereas an increase was found between 1995–1997 and 2005–2007 (range 1.2–4.9%).

Trends in smoking habits between 1995 and 2007

Between 1995–1997 and 2005–2007, the age at first cigarette remained stable in men (approximately 17.5 years) but decreased in women from 21.4 to 18.8 years (Table 2). The proportions of cigarette and pipe smokers decreased in men and the proportion of cigarillo smokers decreased in women. The mean number of cigarettes per day decreased for both men and women. The proportion of current smokers who had attempted to quit decreased significantly in men and women (from about 85 to 75%). Among former smokers, the age at quitting did not change significantly between 1995–1997 and 2005–2007.

Second-hand exposure in never and former smokers

Lastly, second-hand exposure decreased significantly between 1995–1997 and 2005–2007 (Table 3). In men the decrease was marked in the 35–44 years age group, intermediate in the 45–54 years, and insignificant in the 55–64 years group (interaction age group × survey P = 0.003). In women the decrease was not statistically different across the age groups (interaction P = 0.08). Similarly, the mean daily exposure time decreased from more than 2.1 to 4.2 h a day to approximately 2.1–3 h per day in the last survey, without evidence of a significant age × survey interaction.

Discussion

This study reports divergent smoking habit trends in men and women aged 35–64 years during the same time period. Men have reduced their exposure to tobacco from 40 to 24.3%, representing a predicted drop in CHD deaths. In contrast, women have increased their exposure to tobacco during the same time period - resulting in a rise in the predicted CHD death risk estimate.

In men, the prevalence of current smokers decreased by 39% between 1985–1987 and 2005–2007 and was reciprocally associated with a greater prevalence of never smokers. In contrast, the prevalence of current and former women smokers rose and resulted in a 25% decrease in the proportion of women never exposed to tobacco. Similar results have been reported in France for the period 1991–1999, i.e. a significant decrease in tobacco consumption in men and stable levels in women [15].

In 2005–2007, the prevalence of current smokers in the overall 35–64 years age group was still high (24.3 and 20.0% in men and women, respectively). This observation agrees with the results of the ITC France 2005 survey, which reported a prevalence of 30 and 23%, respectively, in men and women aged 15–75 years [16]. Similarly, in the INPES 2005 survey, the prevalence of smoking was 33.3% in men and 26.5% in women aged 12–75 years [17]. The wider age range could explain the higher average prevalence observed in the latter studies, as young adults (and especially young women) smoked more than older participants.

As a result of tobacco exposure changes, the predicted CHD death risk trends were favorable in men and neutral in women. In men, the risk fell by a range of 8.6% and by 5.4% over the periods 1985–1997 and 1995–2007, respectively. In women, the predicted risk fell by 1.4% between 1985–1987 and 1995–1997 but rose by 2.3% between 1995–1995 and 2005–2007. Hence, although the trends were favorable for the late 1980s, they seemed to slow down in the late 1990s. These data suggest that changes in smoking habits could partly explain the decline in CHD deaths seen for male residents of the three MONICA geographical areas. If anything, the smoking trends observed in women would counter the actual reduction in CHD deaths. However, other factors, such as nutritional habits [18], have changed in the past 20 years, which could also affect CHD trends.

The results of this study suggest that major changes have occurred in smoking habits in women less than 35 years of age. Although overall exposure after the age of 35 years changed only slightly, the age at first cigarette decreased from 21.4 to 18.8 years. Over half a century, the age at first cigarette has fallen by 7 years in women and by 2 years in men in France. The fairly stable prevalence of smoking after the age of 35 years is probably linked to planning for pregnancy, pregnancy itself or the presence of children at home. These situations are strong motivators for quitting (at least temporarily) in women. Nevertheless, the smoking habit remains widespread in women aged 44–54 years. In agreement with other reports [17], the prevalence of smoking appeared to have decreased in women aged 35–44 years between 1995–1997 and 2005–2007; this suggests that the unfavorable trends in women observed in the late 1990s might be reversing.

Three observations indicate the presence of favorable trends in smoking habits and exposure between 1995–1997 and 2005–2007. First, the number of cigarettes smoked per day decreased for both sexes. This is consistent with the ITC France survey, which reported an average daily consumption of 13.5 cigarettes per day for French smokers and a higher average daily consumption in males than in females for all age groups [16]. Second, the age at quitting fell slightly for both men and women, although the change was not statistically significant. Third, the extent and duration of second-hand smoke exposure fell, most probably as the result of smoke-free environment laws and a reduction in the overall smoking prevalence in men, a reduction that was more pronounced in young adults. This situation could also contribute to the observed overall reduction in CHD death rates [19–21]. This hypothesis is supported by the estimated effect (a factor of 0.83) of smoke-free laws on myocardial infarction reported in a recent meta-analysis. Taken as a whole, these observations suggest that health prevention is making progress. In contrast, the proportion of current male and female smokers who have attempted to quit decreased significantly from approximately 85 to 75%, suggesting that the remaining smokers are those most likely to resist the influence of health campaigns.

This study has a number of limitations. The MONICA surveys were carried out in three areas that may not be representative of the French population. Socioeconomic factors differ from one region of France to another and therefore risk factors for smoking may differ when comparing our survey population with the French population as a whole. Furthermore, as in other surveys, the participants tended to be slightly more educated than the average population, which may slightly bias the assessment of smoking habits. All the surveys incorporated in this study relied on self-reported smoking status, which may have led to some underestimation of smoking prevalence. With respect to the predicted CHD death rates, no attempts were made to calibrate the SCORE equation for France [22] or to correct for the lag time between exposure and events.

Table 2

Characteristics of current smokers and former smokers and evolution between 1995–1997 and 2005–2007

	Men			Women
	1995–1997	2005–2007	P value∗	1995–1997	2005–2007	P value∗
Current smokers
Age of initiation (years)	17.8 ± 4.0	17.6 ± 4.0	NS	21.4 ± 6.0	18.8 ± 5.0	< 0.0001
Cigarette smokers (%)	27.3	22.2	<0.0002	17.3	18.7	NS
Number of cigarettes (/day)	18.4 ± 12.0	13.9 ± 10.0	<0.0001	13.0 ± 11.0	11.2 ± 8.0	<0.01
Cigarillos smokers (%)	9.4	7.4	NS	1.5	0.5	<0.05
Number of cigarillos (/week)	10.7 ± 23.0	11.9 ± 23.0	NS	2.7 ± 8.0	10.0 ± 15.0	NS
Pipe smokers (%)	2.7	1.1	<0.001	0.2	0.0	ND
Quantity (g/d)	30 ± 41.0	22.7 ± 36.0	NS	3.6 ± 8	0	ND
Quit attempts (%)	87.9	72.0	<0.0001	85.8	74.9	0.002
Number of attempts (n)	2.6 ± 2.0	2.0 ± 2.0	NS	2.6 ± 2.0	2.6 ± 2.0	NS
Former smokers
Age at quit	35.5 ± 10.0	34.4 ± 10.0	NS	35.3 ± 10.0	34.0 ± 10.0	NS

ND, not determined. ∗P>0.05, non-significant.

Table 3

Characteristics of second-hand exposure and evolution between 1995–1997 and 2005–2007

	Men			Women
	1995–1997	2005–2007	P value∗	1995–1997	2005–2007	P value∗
Second-hand exposure in never and former smokers (%)
35-44 (years)	26.5	9.8	<0.0001	29.8	7.6	<0.0001
45-54 (years)	25.1	16.1	0.003	30.1	16.8	<0.0001
55-64 (years)	11.9	10.1	0.37	16.6	9.5	0.0006
Exposure among exposed to second-hand smoke (h/day)
35-44 (years)	3.6 ± 2.9	2.7 ± 2.6	0.13	3.3 ± 2.4	2.6 ± 2.7	0.2
45-54 (years)	3.3 ± 2.8	2.4 ± 2.1	0.02	3.6 ± 3.0	2.5 ± 2.3	0.007
55-64 (years)	2.1 ± 2.0	2.1 ± 1.9	0.94	4.2 ± 3.6	3.0 ± 2.7	0.03

∗P>0.05, non-significant.

In conclusion, this study revealed a favorable trend in the smoking habits of men but increasing tobacco exposure in women. These changes may explain part of the favorable trend in the reduction in male CHD deaths observed between 1985–1987 and 2005–2007 in the French areas monitored in the MONICA survey. However, in 2005–2007, one third of the men and one quarter of the women aged 35–44 years declared themselves to be current smokers. Furthermore, the number of quit attempts in this age group did not rise. A continued decrease in consumption will be highly dependent on maintaining pressure on public opinion and governments for anti-tobacco initiatives.

Footnotes

Acknowledgements

The authors thank the nurses, physicians, dieticians, computer scientists, and secretaries of Lille, Strasbourg and Toulouse and the Centre de Médecine Préventive de Lille, the Laboratoire d'Analyses Génomiques and the Service de Biologie Spécialisée de l'Institut Pasteur de Lille, the Centre de Santé de la MGEN de Strasbourg, the Unité de Coordination de la Biologie des Essais Cliniques des Hôpitaux Universitaires de Strasbourg, the Departments of Cardiology of the Toulouse University Hospital and the city halls, which have participated in the three regions. The third MONICA survey was supported by the Institut National de la Santé et de la Recherche Médicale (INSERM), the Direction Générale de la Santé (DGS), the Fonds d'intervention en Santé Publique, the Mutuelle Générale de l'Education Nationale, ONIVINS, the Fondation de France, the CPAM of Selestat, the Fédération Française de Cardiologie, the Conseil Régional du Nord-Pas de Calais, the Parke-Davis and Bayer pharmaceuticals, and CERIN. The MONA LISA study was made possible by an unrestricted grant of Pfizer and by a grant from ANR (ANR-05-PNRA-018).

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