NEJM: 吸烟使死亡风险增加2倍 34岁之前戒烟可延寿10年

《新英格兰医学杂志》上发表的2项大规模以人群为基础的研究得出了同一结论：吸烟者显然比不吸烟者提前数年死亡。
      
加拿大多伦多全球卫生研究中心的Prabhat Jha博士撰文指出：“分析显示，从不吸烟者活到80岁的几率要比目前吸烟者高出1倍。与从不吸烟者相比，目前吸烟的男性和女性的生存时间分别会缩短12年和11年。”

但这份报告带来的并不全是坏消息。Jha博士指出，在任何时间戒烟都能延长寿命。

研究者分析了参加1997~2004年全美健康访谈调查的113,752名女性和88,496名女性的吸烟和戒烟情况，并将这些数据与截至2006年的全国死亡索引数据进行了关联。然后，研究者计算了25~79岁各年龄段人群的生存率。平均随访时间为7年，在此期间有10,743名受试者死亡。

在校正教育、饮酒和肥胖等因素后，吸烟的男性和女性的死亡风险是不吸烟者的3倍。估算的存活至80岁的几率，女性吸烟者为38%，男性吸烟者为26%，从不吸烟的女性为70%，从不吸烟的男性为61%。

在与吸烟相关的各种疾病上，吸烟男女性的死亡率均明显高于不吸烟者：

·肺癌[男性和女性的危险比(HR)分别为18和15]。

·其他癌症(HR均为2)。

·所有癌症(HR分别为3和4)。

·缺血性心脏病(HR分别为3.5和3)。

·卒中(HR分别为3和2)。

·其他血管疾病(HR分别为8.5和9)。

·呼吸系统疾病(HR均为2)。

·所有内科疾病(HR均为3)。

·意外事故(HR分别为4和2)。

“假如吸烟者的疾病死亡率降至从不吸烟者的水平，那么在25~79岁之间发生的女性吸烟者死亡中的62%和男性吸烟者死亡中的60%是可以避免的。”

另一方面，无论何时戒烟，都可以带来显著的生存获益。在25~34岁之间戒烟者的生存率与从不吸烟者相似。“与继续吸烟者相比，戒烟者可以额外获得大约10年的寿命。”

在35~44岁之间戒烟可以带来9年的生存获益，虽然不如更早戒烟的益处大，但仍然具有显著性。“在39岁左右戒烟者的死亡风险仍然比从不吸烟者高20%，不过远远少于继续吸烟者200%的额外风险。”

在45~54岁之间和55~64岁之间戒烟者，分别可以比继续吸烟者多活6年和4年。“即使在45~54岁之间才戒烟，仍然可使额外的死亡风险减少约2/3。”

研究者称，上述结果与全球其他研究的结果一致。其启示意义非常巨大，对于吸烟率更高、戒烟率更低的低收入国家更是如此。“根据目前的吸烟率和戒烟率估算，20世纪约有1亿人死于吸烟，21世纪将有10亿人因吸烟而死。”

同期发表的另一项研究则首次显示，女性吸烟者与男性吸烟者同样死得早，而且死于同样的疾病。

美国癌症学会(ACS)流行病学专家Michael Thun博士表示：“吸烟者死于肺癌、慢性阻塞性肺病(COPD)、缺血性心脏病、任何类型卒中及全因死亡的相对风险已经基本明确。与男性吸烟方式相同的女性，也会以类似男性的方式死亡。”(N. Engl. J. Med. 2013:368: 351-64)

Thun博士及其同事选取了7项全国性研究和数据库，共包含132万名女性和89.9万名男性。其中2个是历史队列，时间跨度为1959~1988年；5个是当代队列，时间跨度为2000~2010年。随访结束时，受试者的年龄为50~80岁以上不等。

分析结果显示，当代队列中的从不吸烟者的总体生存率优于历史队列中的从不吸烟者，而吸烟者则并未显示出这一年代相关获益。

研究者发现，女性的风险尤其高。“当代队列与历史队列相比，男性吸烟者的全因死亡率降低了23.6%，而女性吸烟者的全因死亡率未见降低。男性吸烟者的肺癌死亡率自20世纪80年代以来一直保持稳定，而女性吸烟者的肺癌死亡率则持续升高。”

Thun博士也发现吸烟者的死亡风险比从不吸烟者增加2倍。吸烟者的死亡中有至少2/3与吸烟直接相关，包括缺血性心脏病、所有其他心脏病、卒中和肺癌。

绝大多数疾病的死亡率高峰是1982~1988年间。自那以后，吸烟者的死亡风险逐渐下降并趋于稳定，但仍然高于从不吸烟者。最明显的是肺癌，男、女性吸烟者的肺癌死亡风险均为不吸烟者的25倍。

与其他疾病死亡率趋于稳定不同的是，吸烟者的COPD死亡风险持续上升。2010~2010年的吸烟者COPD死亡风险超过20世纪80年代队列的2倍以上(RR：25.6 vs. 10)，女性为22.3 vs. 10.3，男性为27.3 vs. 12.5，无明显性别差异。

研究者表示，尚不十分清楚COPD死亡风险上升的原因，无法用老龄化、烟龄或COPD诊断水平提高来解释，或许与烟草生产工艺的变化有关。“例如，混合烟草和烟草作物遗传选择的引入，降低了烟雾的pH值，使得烟雾更易被吸入，需要更深地吸入烟雾才能吸收质子化尼古丁。此外，采用多孔包装纸和有孔过滤嘴，也会稀释烟雾，使吸烟者更多、更深地吸入烟雾，从而增加肺实质的烟雾暴露。”

从组织学角度来看，随着烟草生产工艺的改变，男性吸烟者外周腺癌增加，在很大程度上抵消了鳞状细胞和中心气道小细胞癌的减少。而更深吸入烟雾对于COPD的影响则完全是负面的，因为COPD主要与肺实质损伤有关。

Jha博士的研究由Fogarty国际中心、国立卫生研究院、加拿大卫生研究院和Bill and Melinda Gates基金会资助。Thun博士的研究由国立卫生研究院和美国癌症学会资助。两项研究的作者均无利益冲突披露。

相关评论：无为=伤害

加州大学旧金山分校的Steven Schroeder博士在随刊述评中指出，上述研究带给我们两大启示。(1)从健康获益的角度来看，无论何时戒烟都不算太晚。临床医生，尤其是治疗吸烟相关疾病的医生，应当更努力地鼓励患者戒烟。(2)有必要更加重视吸烟对健康的损害(N. Engl. J. Med. 2013:4: 389-90)。

对某些疾病增加投入的做法值得赞赏，但不能解决主要问题。吸烟者面临被社会边缘化的危险，研究者和政策制定者可能会更加忽视吸烟问题，而我们应当尽可能避免这一情况的发生。正如前澳大利亚卫生部长Nicola Roxon所说，“假如我们不采取行动，就等同于杀人.

21st-Century Hazards of Smoking and Benefits of Cessation in the United States

Extrapolation from studies in the 1980s suggests that smoking causes 25% of deaths among women and men 35 to 69 years of age in the United States. Nationally representative measurements of the current risks of smoking and the benefits of cessation at various ages are unavailable.

METHODS

We obtained smoking and smoking-cessation histories from 113,752 women and 88,496 men 25 years of age or older who were interviewed between 1997 and 2004 in the U.S. National Health Interview Survey and related these data to the causes of deaths that occurred by December 31, 2006 (8236 deaths in women and 7479 in men). Hazard ratios for death among current smokers, as compared with those who had never smoked, were adjusted for age, educational level, adiposity, and alcohol consumption.

RESULTS

For participants who were 25 to 79 years of age, the rate of death from any cause among current smokers was about three times that among those who had never smoked (hazard ratio for women, 3.0; 99% confidence interval [CI], 2.7 to 3.3; hazard ratio for men, 2.8; 99% CI, 2.4 to 3.1). Most of the excess mortality among smokers was due to neoplastic, vascular, respiratory, and other diseases that can be caused by smoking. The probability of surviving from 25 to 79 years of age was about twice as great in those who had never smoked as in current smokers (70% vs. 38% among women and 61% vs. 26% among men). Life expectancy was shortened by more than 10 years among the current smokers, as compared with those who had never smoked. Adults who had quit smoking at 25 to 34, 35 to 44, or 45 to 54 years of age gained about 10, 9, and 6 years of life, respectively, as compared with those who continued to smoke.

CONCLUSIONS

Smokers lose at least one decade of life expectancy, as compared with those who have never smoked. Cessation before the age of 40 years reduces the risk of death associated with continued smoking by about 90%.

Supported by a grant (TW007939-01) from the Fogarty International Center, National Institutes of Health; by a grant (IEG-53506) from the Canadian Institutes of Health Research; and by the Disease Control Priorities Project, Bill and Melinda Gates Foundation. Dr. Jha holds an endowed faculty position at the University of Toronto.

The opinions expressed in this article are those of the authors and do not necessarily represent the opinions of the agencies at which the authors are employed.

Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

We thank Samira Asma, Tom Frieden, Howard Hu, and Arthur Slutsky for useful comments and Jennifer Parker for assistance with the NHIS data.

SOURCE INFORMATION

From the Center for Global Health Research, Toronto (P.J., C.R., V.L.); the Food and Drug Administration, Rockville (B.R.), and the Centers for Disease Control and Prevention, Hyattsville (R.N.A.) — both in Maryland; the American Cancer Society (M.T.) and the Centers for Disease Control and Prevention (T.M.) — both in Atlanta; and the Clinical Trial and Epidemiology Services Unit, University of Oxford, Oxford, United Kingdom (R.P.).

50-Year Trends in Smoking-Related Mortality in the United States

BACKGROUND

The disease risks from cigarette smoking increased in the United States over most of the 20th century, first among male smokers and later among female smokers. Whether these risks have continued to increase during the past 20 years is unclear.

METHODS

We measured temporal trends in mortality across three time periods (1959–1965, 1982–1988, and 2000–2010), comparing absolute and relative risks according to sex and self-reported smoking status in two historical cohort studies and in five pooled contemporary cohort studies, among participants who became 55 years of age or older during follow-up.

RESULTS

For women who were current smokers, as compared with women who had never smoked, the relative risks of death from lung cancer were 2.73, 12.65, and 25.66 in the 1960s, 1980s, and contemporary cohorts, respectively; corresponding relative risks for male current smokers, as compared with men who had never smoked, were 12.22, 23.81, and 24.97. In the contemporary cohorts, male and female current smokers also had similar relative risks for death from chronic obstructive pulmonary disease (COPD) (25.61 for men and 22.35 for women), ischemic heart disease (2.50 for men and 2.86 for women), any type of stroke (1.92 for men and 2.10 for women), and all causes combined (2.80 for men and 2.76 for women). Mortality from COPD among male smokers continued to increase in the contemporary cohorts in nearly all the age groups represented in the study and within each stratum of duration and intensity of smoking. Among men 55 to 74 years of age and women 60 to 74 years of age, all-cause mortality was at least three times as high among current smokers as among those who had never smoked. Smoking cessation at any age dramatically reduced death rates.

CONCLUSIONS

The risk of death from cigarette smoking continues to increase among women and the increased risks are now nearly identical for men and women, as compared with persons who have never smoked. Among men, the risks associated with smoking have plateaued at the high levels seen in the 1980s, except for a continuing, unexplained increase in mortality from COPD.