tobacco: the growing epidemic in china

CVD Prevention and Control (2009) 4, 61–70

www.elsevier.com/locate/precon

Tobacco: The growing epidemic in China

Richard Peto, Zheng-Ming Chen *, Jillian Boreham

Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), Richard Doll Building,Old Road Campus, Roosevelt Drive, University of Oxford, Oxford, UK

Received 2 December 2008; accepted 7 December 2008Available online 20 January 2009

18do

KEYWORDSSmoking;Mortality;Epidemiology;Prospective study;China

75-4570/$ - see front mattei:10.1016/j.cvdpc.2008.12.

* Corresponding author. Tel.E-mail address: zhengming

r � 200001

: +44 18.chen@c

Summary China, with 20% of the world’s population, produces and consumes about30% of the world’s cigarettes, and already suffers about a million deaths a year fromtobacco. This is more than in any other country, and the hazards are expected toincrease substantially during the next few decades, over and above the effects ofdemographic changes, as a delayed effect of the large increase in cigarette usebetween the 1950s and 1990s and of a further sharp increase in cigarette consump-tion since 1999.

In developed countries cigarette smoking became popular during the first half ofthe twentieth century, but the main increase in tobacco deaths was not seen untilseveral decades later, during the second half of the century. In the US, mean ciga-rette consumption per adult in 1910, 1930 and 1950 was 1, 4 and 10 a day, respec-tively, after which it remained fairly constant for a few decades. As a delayed resultof this increase in cigarette smoking, the proportion of all US deaths at ages 35–69attributed to tobacco rose over the next few decades from ‘‘only’’ about 12% in1950 to 33% in 1990.

In Chinese men, the pattern of increase in cigarette smoking that had been seenbetween 1910 and 1950 in the US was repeated 40 years later between 1952 and1992. In most parts of China women now smoke far less than men. Mean cigaretteconsumption per Chinese man in 1952, 1972 and 1992 was 1, 4 and 10 per day,respectively, after which it leveled off for a few years, then continued to rise.Nationwide retrospective and prospective studies in China indicate that by 1990tobacco already caused about 12% of all male deaths at ages 35–69, and by 2030it will probably cause about one third of them, unless there is widespread cessationamong those who already smoke. Although the overall hazard per cigarette smokermay be about the same in China as elsewhere, the chief diseases by which tobaccocaused death in the 1990s were very different in China, with about half of thetobacco deaths involving emphysema rather than cardiovascular disease. The pat-terns of tobacco death also differed between one region and another, and may

8 World Heart Federation. Published by Elsevier Ltd. All rights reserved.

65 743839; fax: +44 1865 743984.tsu.ox.ac.uk (Z.M. Chen).

mailto:[email protected]

Table 1 Increase in cigarette c

All US adults, 1910–1950

Year Cig

1910 11930 41950 10

62 R. Peto et al.

change substantially over time as a result of changes in diet and other factors. Largeprospective epidemiological studies are now in place to monitor the evolution of thegrowing tobacco epidemic in China and elsewhere over the next few decades.� 2008 World Heart Federation. Published by Elsevier Ltd. All rights reserved.

Introduction

In countries such as the United States and the Uni-ted Kingdom, where cigarettes have been usedwidely for several decades, by 1990 smoking wasresponsible for about one third of all deaths in mid-dle age, with about two dozen individual diseases(such as lung cancer, ischemic heart disease,stroke, chronic obstructive pulmonary disease)being causally associated with smoking [1–4].Those who have smoked cigarettes persistentlysince early adulthood are at particularly high risk,with about half of them eventually being killed bytheir habit in middle and old age. In recent decadesthere has been a rapid and substantial increase intobacco consumption in China [5], particularly bymen. With one-fifth of the world’s population, Chi-na now produces and consumes about one third ofthe world’s cigarettes. Although the main increasein cigarette consumption, especially among youn-ger men, has been too recent for its full effectson health yet to be seen, there are already abouta million deaths a year from tobacco in China,which is more than in any other country [6]. Thehazards from tobacco are expected to increasesubstantially during the next few decades as a de-layed effect of the recent rise in cigarette use.Over the past 20 years, three large nationally rep-resentative surveys of smoking prevalence havebeen undertaken by the Chinese Academy of Medi-cal Sciences (CAMS) [7], the Chinese Academy ofPreventive Medicine (CAPM) [8] and the ChineseCentre for Disease Control & Prevention (ChinaCDC) [9] that have provided important informationabout the patterns of and trends in smoking preva-lence in the population. These institutions havealso undertaken, in collaboration with the US orUK, large nationwide retrospective and prospectivestudies of all-cause mortality [10–12]. These, to-

onsumption in China 40 ye

arettes/day

gether with local studies in cities such as Shanghaiand Hong Kong [13–15], where the epidemic maybe particularly advanced, can be used to help as-sess the past, current and future hazards fromtobacco.

Rapid increase in cigarette consumption inChina

A rapid increase in cigarette consumption in Chinahas taken place since the 1970s. Annual domesticcigarette production and consumption increased4-fold over a period of 30 years, from around0.5 trillion cigarettes in 1978 to more than 2 trillionin 2006 [16,17]. Nearly all of the domestically pro-duced cigarettes are consumed in China, with onlyabout 1% being exported. Several factors have con-tributed to this rapid and substantial increase in cig-arette consumption over the last 30 years, includingan increase in population, improved affordability asa result of economic development, a change intaste away from traditional forms of tobacco suchas pipes, the failure to recognize the hazards ofsmoking and lack of effective anti-tobacco legisla-tion. After allowing for population growth therehas been a more than twofold increase in cigaretteconsumption, chiefly due to an increase in cigaretteconsumption per smoker rather than an increase inthe proportion of smokers. A national survey in 1996showed that the total number of smokers in Chinaamounted to over 320 million [8]. Smoking in Chinais largely a male phenomenon, with 67% of mensmoking compared with only 4% of women. Themain increase in cigarette consumption among Chi-nese men during the second half of the twentiethcentury followed a similar pattern to that amongadults in the United States during the first half ofthe century (Table 1). In the US the average ciga-rette consumption per adult in 1910, 1930 and

ars after US increase.

Chinese men, 1952–1992

Year Cigarettes/day

1952 11972 41992 10

Tobacco: The growing epidemic in China 63

1950 was 1, 4 and 10 a day, respectively, afterwhich it remained fairly constant. This pattern ofincrease has been repeated 40 years later in China.Mean cigarette consumption per Chinese man in1952, 1972 and 1992 was likewise 1, 4 and 10 aday, after which it stabilized during the1990s, butthen it began to rise steeply again after 1999 [5].The mean daily consumption per smoker was about15 cigarettes for men in the late 1990s and on aver-age a smoker is estimated to spend about one-quar-ter of his income on cigarettes [8].

Differing smoking trends in men and women

Almost three quarters of Chinese men eventuallybecome smokers. The prevalence rises steeply be-tween ages 15 and 25 and then remains at about70% from age 30–60, after which it declines gradu-ally in men, partly because the smokers are lesslikely to have survived into old age [8,9,11]. Themean age at starting to smoke was about 20 bothfor men who are now in early adult life and formen who are now middle-aged. Among Chinese wo-men the pattern is very different, with the preva-lence depending inversely on the year of birth,being 13%, 4% and 1%, respectively for women bornaround 1930, 1950, and 1970 [8]. Although only 1%of women now aged 25 are smokers, the mean ageat starting for the middle-aged and older femalesmokers was 25 years. Hence, the increase in prev-alence with increasing age is not due to womenstarting to smoke at older age but corresponds toa progressive decrease over the past few decadesin the probability of women starting to smoke.The reasons for this progressive decline in femalesmoking are not clear, and might be due to limitedavailability of tobacco products and changes in so-cial norms since 1950. However, in recent yearssome young women in urban areas have begun tosmoke, and how smoking prevalence among Chi-nese women will change in the future on a nationallevel remains to be seen.

Diminishing difference between urban andrural men

For Chinese men of all ages, smoking is slightlymore common in rural than in urban areas. How-ever there is a large difference between the typesof tobacco smoked by rural and urban men, espe-cially in middle and old age (Fig. 1). In 1991, theproportion of men aged 40 years or more whosmoked cigarettes rather than other types of to-bacco was much higher in urban than in rural areasand much higher in young than in old men [11].

Even those who in 1991 reported smoking ciga-rettes only may have not smoked cigarettes persis-tently throughout their adult life, given the greatfluctuations in Chinese social circumstances duringthe decades before 1980. For the younger popula-tion, however, this urban/rural difference in thetype of tobacco is diminishing rapidly, and almostall young Chinese smokers now smoke only ciga-rettes. In 1996, 99% of urban and 95% of rural malesmokers aged under 30 years smoked cigarettesonly, with a slightly higher proportion of filter cig-arettes smoked by urban smokers, and a recent sur-vey involving more than 500,000 adults in 10different regions of China during 2004–2008 hasconfirmed this [12].

Lack of awareness of smoking hazards in thegeneral population

Whether or not they smoke most Chinese adults arenot fully aware of the hazards of smoking. Evenamong the medical profession the smoking rate ishigh at about 50% for men, and among 150,000adults surveyed in 1996, 30% did not know thatsmoking could cause chronic bronchitis, 60% didnot know that smoking could cause lung cancerand 96% did not know that smoking could causeIHD [8]. Consequently, the proportion of smokerswho were willing to quit or had successfully quitfor over 6 months was low, at 17% and 3.5% respec-tively, with the most common reason for quittingbeing physical illness. Even after quitting, the re-lapse rate was high, with about two-thirds restart-ing within two years. A more recent survey showedthat since mid-1990s there has been some improve-ment in the public knowledge about the hazards ofsmoking in China. For example, the proportion ofadults who are not aware that smokers are at in-creased risk of IHD has dropped from 96% to 78%,while for lung cancer it dropped from 60% to 30%[9]. Although there is still substantial underestima-tion of the magnitude and severity of risks associ-ated with smoking, a high proportion of Chinesepeople strongly support government-enforced to-bacco control policies, including bans on smokingin public places (74%) and on advertising (64%),package health warnings (64%), and bans againstsales to minors (83%) [8].

Tobacco hazards among men born before1950 in China

Over the past 20 years, several large retrospectiveand prospective studies of all-cause mortality have

75 77 7571

44

33

2213

72 6769

656760

57

45

40−49 50−59 60−69 70−79

20

40

60

80

100

0

RuralUrban

Rural

Urban

Any Smoker

Cigarette Smoker

Age:

%

Figure 1 Male smoking prevalence at ages 40–79 in 1991, nationally representative prospective study of 220,000Chinese men aged 40 and over. Note the large difference in the types of tobacco smokers by rural and urban men,especially among the middle and old age groups. By comparison, almost all young smokers aged under 30 now smokemanufactured cigarettes only.

64 R. Peto et al.

been undertaken in China that have providedimportant evidence about the past and currenthazards from tobacco in the Chinese population,especially among men born before 1950.

Fig. 2 shows the urban and rural study areas ofthe first nationwide retrospective study of smok-ing that took place 20 years ago. This involvedinterviewing the families or friends of one millionmen and women throughout mainland China whohad died in 1986–1988 of any cause to determinethe smoking habits of the dead person and thedisease that underlay their death [10]. The smok-ing habits of 0.7 million adults who had died ofvarious neoplastic, respiratory or vascular dis-eases were compared with the habits of the ’con-trol group’ of 0.2 million adults who had died ofother specified diseases, from accidents, or fromother external causes, and an excess risk ofdeath from a particular condition (such as lungcancer) among smokers could be inferred fromthe excess of smokers among those who had diedfrom lung cancer, in comparison with the controldeaths. Similarly, an excess risk of death fromrespiratory and from vascular disease could beinferred.

As the retrospective study was so large, the re-sults for each major category of disease in eachmajor city were separately reliable. For example,the local relative risk, the local prevalence ofsmoking and the local lung cancer rate (standard-ized uniformly for age by averaging the seven deathrates at ages 35–39, 40–44...65–69) in a particularcity could be combined to calculate the absolutelung cancer rates among smokers and non-smokersin that city (Fig. 3).

Lung cancer, which was the first major diseaseto be reliably linked to smoking in Western studies,is also an important hazard for Chinese smokers,but there is unexpectedly wide variation from oneChinese city to another in the magnitude of thishazard. In each city, the lung cancer rate is aboutthree times as great among smokers as amongnon-smokers, but there is a tenfold variation inthe age-standardized non-smoker lung cancer ratesat ages 35–69. In some cities, perhaps chiefly be-cause of domestic heating and cooking fumes,these are ten times as great as the correspondinglung cancer death rates among US non-smokers.There was even wider variation between one cityand another in the non-smoker emphysema deathrates at ages 35–69, which in some cities were al-most 100 times as great as those in US non-smokers.

Fig. 4 shows similar analyses for all neoplastic,all respiratory and all vascular mortality amongmen aged 35–69 in the late 1980s. In each casethere was wide variation between one part of Chinaand another, but in each area the mortality ratewas somewhat greater among smokers than amongnon-smokers.

The two main vascular diseases were ischemicheart disease and stroke and the results for theseare shown in Fig. 5. For both, the smoker versusnon-smoker relative risks were less extreme thanin recent Western studies, but these relative risksmay well change as the epidemic evolves, espe-cially when this is accompanied by substantialchanges in diet in the population. Stroke caused 4times as many deaths as IHD at ages 35–69,whereas in Western countries such as the United

Figure 2 Geographic location of 1986–1988 retrospective study areas in mainland China. For the one million peoplewho died between 1986 and 1988 in 24 cities (named on map) and in 72 rural study areas, the disease that caused deathwas determined and a family member (or other local informant) was interviewed to discover whether in 1980 thedeceased person had been a smoker and, if so, what they had smoked. Smoker versus non-smoker death rate ratiocalculations, standardized for age and study area, were based on case-control comparisons in which the cases werethose who had died from neoplastic, vascular or respiratory causes.


States the opposite is true. In the 1980s the USstroke death rate was lower than the lowest ratein any of these Chinese cities, while the US IHDdeath rate was higher than the highest rate in anyof these cities.

The final panel in Fig. 4 shows the results forall-cause mortality among men who were aged35–69 twenty years ago, in the late 1980s. Thisindicates that at that time about 12% of all maledeaths in China at these ages would have beenavoided if the smokers had had the same mortal-ity rates as the non-smokers. Since mortality ismuch greater at the upper than at the lowerend of the age range 35–69, these findingschiefly reflect the experience of men born aroundthe 1920s, who reached adult life at a time whenrelatively few cigarettes were smoked in Chinaand were dying in 1986–1988 at a time whenischemic heart disease was still relatively uncom-mon. They do not reflect the hazards that the

smokers of today in China will experience in thefuture.

The main findings from this large retrospectivestudy have been confirmed and extended by a largenationally representative prospective study of220,000 men who were recruited at age 40 or aboveduring 1990–1991 and followed for 15 years. Thisprospective study of Chinese men who were bornbefore 1950 shows that the excess mortality associ-ated with smoking accounted for about 12% of alladult male deaths among men born in the 1920sand 1930s [11]. But, there were large differencesbetween urban and rural men. Cigarette consump-tion has been widespread for much longer in urbanthan in rural areas. Consequently the relative risksassociated with smoking were more extreme in ur-ban than in rural areas (Table 2). The relative riskamong those who started smoking before age 20was 1.64, which suggests that 40% (0.64/1.64) ofthese smokers would be killed by tobacco. Contin-

Beijing

Tianjin

Shanghai

Wuhan

Harbin

Changchun

Jilinshi

Shenyang

Dalian

Zibo

Hangzhou

Changsha

Luoyang

Xi’an

Chengdu

Zigong

Chongqing

Guiyang

Guangzhou

Nanjing

Fuzhou+2

Kunming

YangquanHuangshi

Coastal Rural

Inland Rural

0 1 20

1

2

3

Deaths/1000 NON−SMOKERS

Dea

ths/

1000

SM

OK

ERS

lung cancerdeath rate/1000

Male

:Non−smokers SmokersUrban China 0.52 : 1.54Rural China 0.34 : 0.87ALL CHINA 0.39 : 1.07

Beijing

Tianjin

Shanghai

Wuhan

Harbin

ChangchunJilinshi

Shenyang

Dalian

Zibo

Hangzhou

Changsha

Xi’an

Chengdu

Chongqing

Guiyang

GuangzhouNanjing

CoastalRural

Inland Rural

Other urban

0 1 20

1

2

3

Deaths/1000 NON−SMOKERSD

eath

s/10

00 S

MO

KER

S

lung cancerdeath rate/1000

Female

:Non−smokers SmokersUrban China 0.42 : 1.35Rural China 0.24 : 0.47ALL CHINA 0.29 : 0.74

Figure 3 Death rates from lung cancer in various parts of China among men and women aged 35–69 in 1986–1988:ever-smokers versus never-smokers. The lung cancer rates show wide variation, with extremely high rates in somecities among non-smokers and, particularly, among smokers. The rates are standardized to a uniform age distribution.Hence, in the hypothetical absence of any other causes of death, an annual rate of 1.5 per 1000 would correspond to a5% risk of death over this 35-year age range (i.e., to a probability of 5% that a 35-year-old would die of lung cancerbefore age 70). ALL CHINA is calculated as 0.3xurban + 0.7xrural. For comparison, in 1990 the nationwide US lungcancer death rates were 1.4 per 1000 men and 0.6 per 1000 women, and the US non-smoker lung cancer death rate was0.1 per 1000 men or women.

66 R. Peto et al.

ued follow-up of this first nationwide prospectivestudy will also yield useful information aboutthe current decade, but it will yield increasinglylimited information about future decades as itincluded few women and was restricted to peopleborn before 1950.

Tobacco hazards among women in China

Among women, the retrospective study results sug-gest that if they smoke like men they die like men;their overall risks are about the same [10]. But, onthe whole Chinese women do not smoke like men;unexpectedly (and unexplainably), the proportionof women who became smokers before the age of25 has decreased substantially over the past fewdecades [7–9]. If this low uptake of smoking byyoung women continues, then although the propor-tion of deaths attributed to smoking in 1990 and in2030 will increase from 12% to about 33% for Chi-nese men, very much following what was seen inUS adults between 1950 and 1990, it will decrease

from 3% to about 1% for Chinese women (Table 3).Tobacco would then be responsible for most of thedifference in life expectancy between men and wo-men in China.

Future tobacco hazards in Chinese men

The Chinese evidence from the 1980s on tobacconeeds to be seen in the context of Western epide-miological evidence on cigarette smoking, whichdemonstrates the peculiarly long delay betweencause and full effect. In countries such as the UKand US, most of those who now smoke cigarettesbegan to do so in early adult life, and recentUK/US prospective studies show that about halfof all persistent smokers are eventually killed bytheir habit [1–4]. Fifty percent of these tobaccodeaths occur in middle age (here defined as35�69 years), and half in old age. But only thosewho have smoked cigarettes since early adulthoodare at particularly high risk in middle and old age,

Beijing

Tianjin

Shanghai

Wuhan

Harbin

Changchun

Jilinshi

Shenyang

Dalian

Zibo

Hangzhou

Changsha

Luoyang

Xi’an

Chengdu

Zigong

Chongqing

Guiyang

Guangzhou

Nanjing

Fuzhou+2Kunming

Yangquan

Huangshi

Coastal Rural

Inland Rural

0 2 4 60

2

4

6


ALLVASCULARDISEASES

:Non−Smoker SmokerUrban China 3.4:4.0Rural China 3.3:3.7ALL CHINA 3.3:3.8

Beijing

Tianjin

Shanghai

Wuhan

Harbin

Changchun

Jilinshi

Shenyang

Dalian

ZiboHangzhou

Changsha

Luoyang

Xi’an

Chengdu

ZigongChongqing Guiyang

Guangzhou

NanjingFuzhou+2

Kunming

Yangquan

Huangshi

Coastal Rural

Inland Rural

0 6 12 180

6

12

18


Dea

ths/

1000

SM

OK

ERS

ALLCAUSES

OF DEATH:Non−Smoker Smoker

Urban China 9.7:12.8Rural China 14.3:17.7ALL CHINA 12.9:16.2

Beijing

Tianjin

Shanghai

Wuhan

Harbin

Changchun

Jilinshi

Shenyang

Dalian

Zibo

Hangzhou

Changsha

Luoyang

Xi’an

ChengduZigong

Chongqing

Guiyang

Guangzhou

Nanjing

Fuzhou+2

Kunming

Yangquan

Huangshi

Coastal Rural

Inland Rural

0 2 4 60

2

4

6


ALLNEOPLASTIC

DISEASES:Non−Smoker Smoker


Beijing

Tianjin

Shanghai

Wuhan

HarbinChangchun

JilinshiShenyang

Dalian

ZiboHangzhou

Changsha

Luoyang

Xi’an

Chengdu

Zigong

Chongqing

Guiyang

Guangzhou

NanjingFuzhou+2

Kunming

Yangquan

Huangshi

Coastal Rural

Inland Rural

0 2 4 60

2

4

6

Deaths/1000 NON−SMOKERSD

eath

s/10

00 S

MO

KER

S

ALLRESPIRATORY

DISEASES:Non−Smoker Smoker


Figure 4 Death rates from all neoplastic disease, all respiratory disease, all vascular disease and all causes amongmen aged 35–69 in 1986–1988: ever-smokers versus never-smokers. Methods as in Fig. 3. Calculations of the effects ofsmoking on all-cause mortality sum the effects on neoplastic, respiratory and vascular mortality, and assume no effecton other mortality. For comparison, in 1990 the US death rates per 1000 men were 3.5 neoplastic, 0.7 respiratory, 4.3vascular and 11.2 all causes.


so earlier UK/US prospective studies – conductedafter the rise in cigarette use but only halfwaythrough the increase in mortality – misleadinglysuggested that the risks of tobacco use were low-

er. The need for prolonged smoking before the fullrisks become evident means that if a countryexperiences a nationwide surge in cigarette useby young adults then this will cause a large in-

BeijingTianjin

ShanghaiWuhan

Harbin

Changchun

Jilinshi

Shenyang

DalianZibo

Hangzhou

Changsha

Luoyang

Xi’an

Chengdu

Zigong

ChongqingGuiyang

Guangzhou

NanjingFuzhou+2KunmingYangquan

Huangshi

Coastal RuralInland Rural

0 1 2 30

1

2

3


IHD:Non−Smoker Smoker


Beijing

Tianjin

Shanghai

Wuhan

Harbin

Changchun

Jilinshi

Shenyang

Dalian

Zibo

Hangzhou

Changsha

Luoyang

Xi’an

Chengdu

Zigong

Chongqing

Guiyang

Guangzhou

Nanjing

Fuzhou+2Kunming

Yangquan

HuangshiCoastal Rural

Inland Rural

0 2 4 60

2

4

6


Dea

ths/

1000

SM

OK

ERS

STROKE:Non−Smoker Smoker


Figure 5 Death rates from ischemic heart disease (IHD) and stroke among men aged 35–69 in 1986–1988: ever-smokers versus never-smokers. Methods as in Fig. 3. For comparison, in 1990 the US death rates per 1000 men were 2.5IHD and 0.4 stroke.

68 R. Peto et al.

crease in tobacco deaths about half a century la-ter. Until then, however, there may be severaldecades during which cigarette consumption ishigh but mortality from tobacco is still relativelylow [3].

In China, studies of the mortality rates around1990 suggested that only about a quarter of smokerswho start before age 20 will be killed by tobacco[10,11]. This reflected the fact that at that timethe older men had not smoked persistently, or hadsmoked forms of tobacco that carry a lower riskthan cigarettes (Fig. 1), but smoker/non-smokermortality ratios are likely to increase. Indeed, in ur-ban areas, where a greater proportion of tobaccouse involves cigarettes, the risk ratio for thosewho began smoking before age 20 was alreadyapproaching 2, suggesting that about a half of allsuch smokers would be killed by tobacco [11,12–15]. In the Chinese population of Hong Kong, ciga-rette consumption reached its peak about 20 yearsearlier than in mainland China but about 20 yearslater than in the United States. A large popula-tion-based retrospective study found that in thelate 1990s smoking was a cause of about one-thirdof all male deaths in Hong Kong [15]. Although notnationally representative of China, this Hong Kongstudy is important for China as a whole because itillustrates how large the hazards of smoking caneventually become in an ethnically Chinese popula-

tion, and foreshadows the proportion of maledeaths in middle age that could be caused by smok-ing in China as a whole in the late 2020s if currentsmoking patterns persist.

From a public health perspective, the main find-ing of the Chinese study is the alarming overall riskof death already associated with smoking. Abouttwo thirds of young Chinese men become cigarettesmokers in early adult life, and it is possible that inChina, as in America, about half of those who do sowill eventually be killed by their habit. If so, then,about one third of all young Chinese men will even-tually, in middle or old age, be killed by tobacco.As about 10 million a year are currently reachingmanhood in China, the annual number of tobaccodeaths will rise from about 1 million now to about3 million in the middle of the present century.Hence, if the current high uptake rates and lowcessation rates persist, there will be a total ofabout 100 million deaths caused by tobacco in Chi-na during the first half of the present century.

But, even if the overall 50% hazard will be aboutthe same in China as elsewhere, the Chinese stud-ies show that the chief diseases by which tobaccocaused death were very different in China (and,within China, between one city and another) fromthose elsewhere, and may change substantially inthe future. In the United States, for example, to-bacco causes far more deaths from heart attacks

Table 2 Smoking and all-cause mortality in a nationally representative sample of 220,000 men in mainland Chinawho were born before 1950.

No. of study deaths at ages 40–79 years Deaths attributed tosmoking (%)Never smoked Ever smoked Relative risk (& 95% CI)

Urban 2020 5876 1.38* (1.31–1.46) 1618/7896 (20%)Rural 7480 25,473 1.14 (1.11–1.17) 3167/32,953 (10%)Total 9500 31,349 1.19 (1.16–1.22) 4785/40,849 (12%)* Among the urban men who began smoking some form of tobacco before age 20 and who ever smoked some cigarettes there were1530 deaths at ages 40–79 and the relative risk was 1.64 (1.52–1.76), suggesting that almost 40% of these deaths were smoking-associated (i.e., would have been avoided if ever-smokers had the same age-specific death rates as never-smokers).

Table 3 Delayed hazard: proportion of all deaths at ages 35–69 due to tobacco in US and China.

US: All adults (%) China: Men (%) Women (%)

1950 12 1990 12 31990 33 2030 �33 1


than from emphysema, whereas in China the oppo-site is true. Of Chinese tobacco deaths in the1980s, almost half involved emphysema, and theproportions involving tuberculosis, esophageal can-cer, stomach cancer and liver cancer were eachabout as large (5–8%) as the proportions involvingheart disease or stroke.

The only hope of substantially limiting tobaccodeaths in China (as well as elsewhere) in the firsthalf of this century is for many of the adults whonow smoke to stop doing so, because discouragingyoung people from starting will take many decadesto produce its main health benefits. Western stud-ies show that, even in middle age, cessation ofsmoking is remarkably effective, removing muchof the 50% risk of death from persistent tobaccosmoking [1–4]. Stopping at earlier ages is evenmore effective. Britain, which is now experiencingthe most rapid decrease in the world in prematuredeaths from tobacco, shows that large improve-ments are possible: over the past 30 years, UK cig-arette sales have halved, and UK tobacco deaths inmiddle age have decreased by more than half [3].In the 1990s, however, such changes were chieflylimited to Western smokers; Chinese smokers, forexample, rarely stopped until they were too ill tocontinue [8,9].

Large prospective studies to monitor thegrowing tobacco epidemic

The recent substantial increase in cigarette con-sumption by Chinese men will eventually cause asubstantial increase in mortality. However, with-out large population-based prospective studies of

young and middle-aged adults, the long-term evo-lution of the epidemic of tobacco deaths in China,as well as in many other developing countries, issomewhat unpredictable, especially since therewill be substantial changes in diet, indoor airpollution and chronic infective processes in futuredecades. Hence, the background rates amongnon-smokers may change unpredictably in waysthat also change the absolute effects of tobacco.

Partly to help monitor the evolution of the grow-ing tobacco epidemic in China, a new large pro-spective study was established during 2004–2008[12]. It involves 200,000 men and 300,000 womenaged over 35 (i.e., born before about 1970) from10 regions across China, with extensive data collec-tion on smoking and other potential risk exposures,as well as long-term storage of blood samples. Fol-low-up is only just beginning and will continue fordecades, recording not only mortality but also allepisodes of illness that require hospitalization. Thisnew prospective study will provide reliable evi-dence about the nationwide hazards among thoseborn in the 1930s, 1940s, 1950s and 1960s, as theepidemic of illness and death from tobacco evolvesin China. Unless there is widespread cessation,however, even greater hazards are likely to beexperienced by those born in the 1970s. Theyreached adult life in the 1990s, when nationwidemale cigarette consumption was high, and largenumbers of young men were starting to smoke sub-stantial amounts even before reaching adult life.This large study will help us to sort out the comple-mentary roles of nature and nurture (e.g., smok-ing, diet, chronic infections, etc) as major causesof chronic diseases in China.

70 R. Peto et al.

Summary

About two thirds of young Chinese men becomecigarette smokers in early adult life, and in China,as in America, about half of those who do so willeventually be killed by their habit if they continue.Although the main increase in cigarette consump-tion in China has been too recent for its full effectson health yet to be seen, there are already about amillion deaths a year from tobacco in China, whichis more than in any other country. The hazardsfrom tobacco are expected to increase substan-tially during the next few decades as a delayed ef-fect of the recent rise in cigarette use. Reducingthe uptake of smoking by children will chiefly yieldbenefits only in the middle and second half of thepresent century, so the main way of substantiallylimiting tobacco deaths over the next few decadesis for many of the adults who now smoke to stopdoing so. In addition to measures such as betterpublic information on smoking hazards, prominenthealth warning labels on cigarette packs, banningsmoking in public places, and improved availabilityof smoking cessation clinics, higher taxation of to-bacco products, a control measure that is vastlyunder-utilized in China, could be of substantialpublic health importance.

References

[1] Peto R, Lopez A, Boreham J, Thun M, Heath C. Mortalityfrom tobacco in developed countries: indirect estimationfrom national vital statistics. Lancet 1992;339:1268–78.updated on http://www.deathsfromsmoking.net (accessed11.11.2008).

[2] US Department of Health & Human Services. Reducing thehealth consequences of smoking: 25 years of progress. Areport of the surgeon general. US Department of Health &Human Services, Public Health Service, Centers for Disease

Control, Center for Chronic Disease Prevention and HealthPromotion, Office on Smoking and Health. DHHS PublicationNo. (CDC) 89-8411; 1989.

[3] IARC. The hazards of smoking and the benefits of stopping:cancer mortality and overall mortality. IARC Handbooks ofCancer Prevention. Tobacco Control, vol. 11. Reversal ofrisk after quitting smoking. Lyon, France; 2007. p. 15–27

[4] Doll R, Peto R, Boreham J, Sutherland I. Mortality inrelation to smoking: 50 years observations on male Britishdoctors. BMJ 2004;328:1519–39.

[5] Yang GH, Kong LZ, Zhao WH, Wan X, Zhai Y, Chen LC, et al.Emergence of chronic non-communicable diseases in China.Lancet 2008;372:1697–705.

[6] Peto R, Chen ZM, Boreham J. Tobacco – the growingepidemic. Nature Med 1999;1:15–7.

[7] Weng XZ, Hong ZG, Chen DY. Smoking prevalence inChinese aged 15 and above. Chin Med J (Engl)1987;100:886–92.

[8] Yang GH, Fan LX, Tan J, Qi GM, Zhang YF, Samet JM, et al.Smoking in China: findings of the 1996 National PrevalenceSurvey. JAMA 1999;282:1247–53.

[9] Yang GH, Ma JM, Liu N, Zhou LN. Smoking and passivesmoking in Chinese, 2002. Chin J Epidemiol 2005;26:77–83.

[10] Liu BQ, Peto R, Chen ZM, Boreham J, Wu YP, Li JY, et al.Emerging tobacco hazards in China: 1. Retrospectiveproportional mortality study of one million deaths. BMJ1998;317:1411–22.

[11] Niu SR, Yang GH, Chen ZM, Wang JL, Wang GH, He XZ, et al.Emerging tobacco hazards in China: 2. Early mortalityresults from a prospective study. BMJ 1998;317:1423–4.

[12] Chen ZM, Li LM, Chen JS, Collins R, Wu F, Guo Y, et al.Cohort proflie: the Kadoorie study of chronic disease inChina (KSCDC). Int J Epidemiol 2005;34:1243–9.

[13] Yuan JM, Ross RK, Wang XL, Gao YT, Henderson BE, Yu MC,et al. Morbidity and mortality in relation to cigarettesmoking: a prospective male cohort study in Shanghai,China. JAMA 1996;275:1646–50.

[14] Chen ZM, Xu Z, Collins R, Li WX, Peto R. Early health effectsof emerging tobacco epidemic in China: a 16-year prospec-tive study. JAMA 1997;278:1500–4.

[15] Lam TH, Ho SY, Hedley AJ, Mak KH, Peto R. Mortality andsmoking in Hong Kong: a case-control study of all adultdeaths in 1998. BMJ 2001;323:1–3.

[16] Huang XL, editor. The China tobacco history. Beijing,China: China Press; 2006.

[17] Huang XQ. Tobacco economic in 2007. China tobacco2008;3:59.

Available online at www.sciencedirect.com�

http://www.deathsfromsmoking.net

tobacco: the growing epidemic in china

Documents