Critchley J, Capewell S
International Health Research Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK, L3 5QA.
Cochrane Database Syst Rev. 2004(1):CD003041. doi: 10.1002/14651858.CD003041.pub2.
Although the importance of smoking as a risk factor for coronary heart disease is beyond doubt, the speed and magnitude of risk reduction when a smoker with coronary heart disease quits are still subjects of debate.
To estimate the magnitude of risk reduction when a patient with CHD stops smoking.
We searched the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index, CINAHL, PsychLit, Dissertation Abstracts, BIDS ISI Index to Scientific and Technical Proceedings, UK National Research Register from the start of each database. Sixty-one large international cohort studies of cardiovascular disease were identified, and contact made with authors to search for any unpublished results. The search was supplemented by cross-checking references and contact with various experts. Date of last search was April 2003.
Any prospective cohort studies of patients with a diagnosis of CHD, which include all-cause mortality as an outcome measure. Smoking status must be measured on at least two occasions to ascertain which smokers have quit, and followed-up for at least two years.
Eligibility and trial quality were assessed independently by two reviewers.
Twenty studies were included. There was a 36% reduction in crude relative risk (RR) of mortality for those who quit smoking compared with those who continued to smoke (RR 0.64, 95% confidence interval 0.58 to 0.71). There was also a reduction in non-fatal myocardial infarctions (crude RR 0.68, 95% confidence interval 0.57 to 0.82). Many studies did not adequately address quality issues, such as control of confounding, and misclassification of smoking status. However, there was little difference in the results for the six 'higher quality' studies, and little heterogeneity between these studies. This review was not able to assess how quickly the risk of mortality was reduced.
REVIEWER'S CONCLUSIONS: Quitting smoking is associated with a substantial reduction in risk of all-cause mortality among patients with CHD. The pooled crude RR was 0.64 (95% CI 0.58 to 0.71). This 36% risk reduction appears substantial compared with other secondary preventive therapies such as cholesterol lowering which have received greater attention in recent years. The risk reduction associated with quitting smoking seems consistent regardless of differences between the studies in terms of index cardiac events, age, sex, country, and time period. However, relatively few studies have included large numbers of older people, women, or people of non-European descent, and most were carried out in Western countries.
尽管吸烟作为冠心病危险因素的重要性毋庸置疑，但冠心病吸烟者戒烟后风险降低的速度和幅度仍存在争议。
评估冠心病患者戒烟后风险降低的幅度。
我们检索了Cochrane对照试验注册库（CENTRAL）、MEDLINE、EMBASE、科学引文索引、护理学与健康领域数据库（CINAHL）、心理学文摘数据库（PsychLit）、学位论文摘要数据库、BIDS科学与技术会议录ISI索引、英国国家研究注册库，检索起始时间为各数据库建库之初。共识别出61项大型国际心血管疾病队列研究，并与作者联系以查找未发表的研究结果。通过交叉核对参考文献和与各位专家联系对检索进行补充。最后一次检索时间为2003年4月。
任何对诊断为冠心病患者的前瞻性队列研究，研究需将全因死亡率作为结局指标。吸烟状况必须至少测量两次以确定哪些吸烟者已戒烟，并随访至少两年。
两名评价员独立评估研究的纳入资格和质量。
纳入20项研究。与继续吸烟者相比，戒烟者的粗相对危险度（RR）降低了36%（RR 0.64，95%置信区间0.58至0.71）。非致死性心肌梗死也有所减少（粗RR 0.68，95%置信区间0.57至0.82）。许多研究未充分解决质量问题，如混杂因素的控制和吸烟状况的错误分类。然而，六项“高质量”研究的结果差异不大，这些研究之间几乎没有异质性。本综述无法评估死亡率风险降低的速度。
戒烟与冠心病患者全因死亡率风险的大幅降低相关。合并后的粗RR为0.64（95%CI 0.58至0.71）。与近年来受到更多关注的其他二级预防疗法如降低胆固醇相比，这种36%的风险降低似乎幅度很大。无论研究在索引心脏事件、年龄、性别、国家和时间段方面存在差异，戒烟带来的风险降低似乎是一致的。然而，相对较少的研究纳入了大量老年人、女性或非欧洲裔人群，且大多数研究在西方国家开展。
