Smoking cessation for the secondary prevention of coronary heart disease

 

Abstract

Background

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.

Objectives

To estimate the magnitude of risk reduction when a patient with CHD stops smoking.

Search methods

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international cohort studies of cardiovascular disease were identified, and contact made with authors to search for any unpublished results.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.

Selection criteria

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.

Data collection and analysis

Eligibility and trial quality were assessed independently by two reviewers.

Main results

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 (CI) 0.58 to 0.71). There was also a reduction in non-fatal myocardial infarctions (crude RR 0.68, 95% CI 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.

Authors' 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.

 

Plain language summary

People who quit smoking after a heart attack or cardiac surgery reduce their risk of death by at least one third

Smoking is harmful for the heart and circulation. People who have had a heart attack or cardiac surgery are at increased risk of further life-threatening heart problems, including death from heart attack. The review found strong evidence that quitting smoking after a heart attack or cardiac surgery can decrease that person's risk of death by at least one third. The beneficial impact of quitting smoking after serious heart disease may be as great or greater than other possible interventions (such as cholesterol-lowering medications).

 

摘要

背景

戒菸作為冠狀動脈疾病之次級預防

雖然吸煙無疑是影響冠狀動脈血管疾病的一個重要因子，但當癮君子合併有冠狀動脈血管疾病時，戒菸，對於減低冠狀動脈血管疾病危險的速度與重要程度，仍是一個至今重要的討論課題。

目標

評估當癮君子合併有冠狀動脈疾病時，戒菸對於減低冠狀動脈血管疾病危險的重要程度。

搜尋策略

本研究資料收集包含Cochrane Register of Controlled Trials (CENTRAL)、MEDLINE、EMBASE、Science Citation Index、CINAHL、PsychLit、Dissertation Abstracts、BIDS ISI Index to Scientific、Technical Proceedings，以及UK National Research Register (從開始研究之數據)，此外還找出61個大型國際心血管疾病之世代研究，我們連絡作者以取得未發表的數據並且利用交叉核對文獻以及詢問專家來補充搜尋。整體數據收集至2003/04

選擇標準

本論文囊括許多CHD病人前瞻性世代研究，其中。其結果必須包含全原因死亡率，並且少有2個時點來評估癮君子的吸煙情況，以確定哪一位癮君子已戒菸，並且至少要追蹤兩年以上的時間。

資料收集與分析

對於納入實驗數據之合格與品質認定，是授權兩個獨立的檢閱者。

主要結論

本論文囊括20個實驗。其中，原始資料顯示，相較持續抽菸的人，戒煙可以減少36 %的死亡率(RR0.64,95C1 0.58 – 0.71)，同時，也發現到，即使情況屬於非致命性之心肌梗塞，發生率也有下降的情形(RR0.68,95% C1 0.57 – 0.82)。但很可惜，在許多實驗中，並沒有詳盡地強提到品質的議題，比如要如何控制干擾因子(confouhding)以及分類，癮君子吸煙的狀況。相對地，其中還是有6個品質較高的研究結果有所差異並且這些數據中，彼此間仍存在些許多的異質性，並且造成些許不一樣的結果。故本研究並不能評估戒菸的成果能在多短的時間內，減少死亡之危險性。

作者結論

戒菸可以確實減少，罹患冠狀動脈血管疾病病人之全原因死亡率，原始資料顯示，危險指標是0.64 (95%信賴區間，由0.58至0.71)，也就是表示，戒煙可以減少36 %的死亡率，相對於近幾年，其它有關於冠狀動脈血管疾病與次級預防的研究，包括降低膽固醇…等，戒菸所造成之影響更值得注意。戒菸與減少罹患冠狀動脈血管疾病之風險，是不受限於心臟狀況、年紀、性別、國家、以及時間。另外，在西方國家，還有少數實驗囊括更多人數，針對老年人、女人、非歐洲人血統的研究。

翻譯人

本摘要由臺北榮民總醫院項國威翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

對於曾經罹患心血管疾病或接受心血管手術的病人，戒菸至少可以降低1/3的死亡率。 吸菸是有害於心臟以及循環系統，尤其對於曾經罹患心血管疾病或接受心血管手術的病人，吸菸會增加死於心臟病之機會。本研究有強烈的證據顯示，對於曾經罹患心血管疾病或接受心血管手術的病人，戒菸至少可以降低1/3的死亡率。甚至，對於罹患重大心臟疾病的病人，戒菸與其他因子(如降低膽固醇的藥物)比較，戒菸能給予更大的改善空間。