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Smoking Status: Effects on Heart and Blood Vessels & Meta Data Analysis on Death from Lung Cancer

Posted in Atherogenic Processes & Pathology, CANCER BIOLOGY & Innovations in Cancer Therapy, Cardiovascular Research, Frontiers in Cardiology and Cardiovascular Disorders, HTN, Origins of Cardiovascular Disease, Population Health Management, Genetics & Pharmaceutical, Population Health Management, Nutrition and Phytochemistry, Statistical Methods for Research Evaluation, tagged Meta Data Analysis on January 9, 2014| Leave a Comment »

Smoking Status: Effect on Heart and Blood Vessels & Meta Data Analysis on Death from Lung Cancer

Curator: Aviva Lev-Ari, PhD, RN

This article has TWO parts:

Part 1: Smoking Effects on Cardiovascular Diseases

and

Part 2: Incidence-Rate Ratios for Death from Any Cause and Death from Lung Cancer, According to Smoking Status – Meta Data Analysis

Part 1

Smoking Effect on Cardiovascular Diseases

Not Smoking as Part of a Heart Healthy Lifestyle

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/lifestyle.html

How Does Smoking Affect the Heart and Blood Vessels?

Cigarette smoking causes about 1 in every 5 deaths in the United States each year. It’s the main preventable cause of death and illness in the United States.

Smoking harms nearly every organ in the body, including the heart, blood vessels, lungs, eyes, mouth, reproductive organs, bones, bladder, and digestive organs. This article focuses on how smoking affects the heart and blood vessels.

Other Health Topics articles, such as COPD (chronic obstructive pulmonary disease),Bronchitis, and Cough, discuss how smoking affects the lungs.

Overview

Smoking and Your Heart and Blood Vessels

The chemicals in tobacco smoke harm your blood cells. They also can damage the function of your heart and the structure and function of your blood vessels. This damage increases your risk of atherosclerosis (ath-er-o-skler-O-sis).

Atherosclerosis is a disease in which a waxy substance called plaque (plak) builds up in the arteries. Over time, plaque hardens and narrows your arteries. This limits the flow of oxygen-rich blood to your organs and other parts of your body.

Coronary heart disease (CHD) occurs if plaque builds up in the coronary (heart) arteries. Over time, CHD can lead to chest pain, heart attack, heart failure,arrhythmias (ah-RITH-me-ahs), or even death.

Smoking is a major risk factor for heart disease. When combined with other risk factors—such as unhealthy blood cholesterol levels, high blood pressure, and overweight or obesity—smoking further raises the risk of heart disease.

Smoking also is a major risk factor for peripheral arterial disease (P.A.D.). P.A.D. is a condition in which plaque builds up in the arteries that carry blood to the head, organs, and limbs. People who have P.A.D. are at increased risk for heart disease, heart attack, and stroke.

Smoking and Atherosclerosis

The image shows how smoking can affect arteries in the heart and legs. Figure A shows the location of coronary heart disease and peripheral arterial disease. Figure B shows a detailed view of a leg artery with atherosclerosis—plaque buildup that’s partially blocking blood flow. Figure C shows a detailed view of a coronary (heart) artery with atherosclerosis.

Any amount of smoking, even light smoking or occasional smoking, damages the heart and blood vessels. For some people, such as women who use birth control pills and people who have diabetes, smoking poses an even greater risk to the heart and blood vessels.

Secondhand smoke also can harm the heart and blood vessels. Secondhand smoke is the smoke that comes from the burning end of a cigarette, cigar, or pipe. Secondhand smoke also refers to smoke that’s breathed out by a person who is smoking.

Secondhand smoke contains many of the same harmful chemicals that people inhale when they smoke. Secondhand smoke can damage the hearts and blood vessels of people who don’t smoke in the same way that active smoking harms people who do smoke. Secondhand smoke greatly increases adults’ risk of heart attack and death.

Secondhand smoke also raises children and teens’ risk of future CHD because it:

Lowers HDL cholesterol (sometimes called “good” cholesterol)
Raises blood pressure
Damages heart tissues

The risks of secondhand smoke are especially high for premature babies who haverespiratory distress syndrome (RDS) and children who have conditions such as asthma.

Researchers know less about how cigar and pipe smoke affects the heart and blood vessels than they do about cigarette smoke.

However, the smoke from cigars and pipes contains the same harmful chemicals as the smoke from cigarettes. Also, studies have shown that people who smoke cigars are at increased risk for heart disease.

Benefits of Quitting Smoking and Avoiding Secondhand Smoke

One of the best ways to reduce your risk of heart disease is to avoid tobacco smoke. Don’t ever start smoking. If you already smoke, quit. No matter how much or how long you’ve smoked, quitting will benefit you.

Also, try to avoid secondhand smoke. Don’t go to places where smoking is allowed. Ask friends and family members who smoke not to do it in the house and car.

Quitting smoking will reduce your risk of developing and dying from heart disease. Over time, quitting also will lower your risk of atherosclerosis and blood clots.

If you smoke and already have heart disease, quitting smoking will reduce your risk ofsudden cardiac death, a second heart attack, and death from other chronic diseases.

Researchers have studied communities that have banned smoking at worksites and in public places. The number of heart attacks in these communities dropped quite a bit. Researchers think these results are due to a decrease in active smoking and reduced exposure to secondhand smoke.

Outlook

Smoking or exposure to secondhand smoke damages the heart and blood vessels in many ways. Smoking also is a major risk factor for developing heart disease or dying from it.

Quitting smoking and avoiding secondhand smoke can help reverse heart and blood vessel damage and reduce heart disease risk right away.

Quitting smoking is possible, but it can be hard. Millions of people have successfully quit smoking and remained nonsmokers. A variety of strategies, programs, and medicines are available to help you quit smoking.

Not smoking is an important part of a heart healthy lifestyle. A heart healthy lifestyle also includes following a healthy diet, maintaining a healthy weight, and being physically active.

SOURCE

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/

What Are the Risks of Smoking?

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/risks.html

What Are the Benefits of Quitting Smoking?

One of the best ways to reduce your risk of coronary heart disease is to avoid tobacco smoke. Don’t ever start smoking. If you already smoke, quit. No matter how much or how long you’ve smoked, quitting will benefit you.

Also, try to avoid secondhand smoke. Don’t go to places where smoking is allowed. Ask friends and family members to not smoke in the house and car.

Quitting smoking will benefit your heart and blood vessels. For example:

Heart disease risk associated with smoking begins to decrease soon after you quit. It continues to decrease over time. Your risk is cut in half 1 year after quitting. If you have not developed heart disease within 15 years of quitting, your risk is nearly the same as the risk in someone who has never smoked.
Deaths from heart disease are reduced by one-third in people who quit smoking compared with people who continue smoking. Repeat heart attacks are reduced by about the same amount.
People who smoke and already have heart disease lower their risk of sudden cardiac death, second heart attacks, and death from other chronic diseases by as much as half if they quit smoking.
Your risk of atherosclerosis and blood clots declines over time after you quit smoking.

Quitting smoking can lower your risk of heart disease as much as, or more than, common medicines used to lower heart disease risk, including aspirin, statins, beta-blockers, and ACE inhibitors.

In recent years, communities in Montana, Colorado, New York, Massachusetts, Indiana, and Ohio have banned smoking at worksites and in public places. Some countries, including Italy, Ireland, Norway, Scotland, and France, have put similar bans in place.

Studies of these communities show a rapid drop in the number of heart attacks within the first year of the ban. The number of heart attacks continues to decrease as time goes on.

Researchers think these results are due to a decrease in active smoking and reduced exposure to secondhand smoke.

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/benefits.html

Strategies To Quit Smoking

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/strategies.html

Clinical Trials

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/trials.html

Links to Other Information About Smoking and Your Heart

http://www.nhlbi.nih.gov/health/health-topics/topics/smo/links.html

Part 2

Incidence-Rate Ratios for Death from Any Cause and Death from Lung Cancer, According to Smoking Status

CORRESPONDENCE

Meta-Analysis and the Surgeon General’s Report on Smoking and Health

N Engl J Med 2014; 370:186-188January 9, 2014DOI: 10.1056/NEJMc1315315

http://www.nejm.org/doi/full/10.1056/NEJMc1315315?query=TOC

To the Editor:

Fifty years ago, on January 11, 1964, the landmark report on smoking and health1 was made public by U.S. Surgeon General Luther L. Terry. That report made substantial use of a meta-analysis performed by statistician William G. Cochran,2,3 who was a professor of statistics at Harvard University. Cochran had already developed statistical methods for various applications, including for the combination of results from different experiments.2 As an author of the report, Cochran followed the major steps for a modern systematic review, including a meta-analysis based on data on individual participants in seven large, prospective cohort studies that had been initiated in the 1950s. Although Cochran used modern state-of-the-art statistical methods, the presentation of the results with confidence intervals was rarely done at that time.

Using summary data provided in the report, we reconstructed Cochran’s meta-analysis, concentrating on death from any cause and death from lung cancer (Figure 1FIGURE 1Incidence-Rate Ratios for Death from Any Cause and Death from Lung Cancer, According to Smoking Status.). The results, produced with the R statistical package meta, version 3.1-2,4 show the contributions of the individual studies (for a list of the full names of the studies, see the Supplementary Appendix, available with the full text of this letter at NEJM.org). The magnitude and precision of the effects of cigarette smoking and their consistency over studies were major criteria for Cochran.1 In our analysis, the test of heterogeneity yielded a nonsignificant result for lung-cancer mortality and a significant result for all-cause mortality, with a small between-study variance. The statistical method we used to create this forest plot was slightly different from the one Cochran used, but it provided almost identical results. When added to the tables in the Surgeon General’s report, Figure 1 shows a dramatic summary of the overwhelming evidence of the harmful effects of cigarette smoking. These findings should be interpreted in light of the fact that before the report was released, as noted by Meier,3 “some of the most eminent statisticians (including Sir Ronald A. Fisher), emphasizing the potential biases in the observational material, declared that no reasonable conclusion adverse to cigarette smoking could be drawn from the available evidence.”

Cochran took an impartial systematic approach to evaluation and used a sensitivity analysis to perform a thorough appraisal of risk of bias. The first meta-analyses in medicine were conducted at the beginning of the 20th century; however, their major breakthrough came only with the activities of the Cochrane Collaboration during the 1990s.5 Although it is widely recognized that the Surgeon General’s report on smoking and health is important for public policy, the importance of this report for meta-analysis is often overlooked and also warrants attention.

Martin Schumacher, Ph.D.
Gerta Rücker, Ph.D.
Guido Schwarzer, Ph.D.
University Medical Center Freiburg, Freiburg, Germany
ms@imbi.uni-freiburg.de

References

1Smoking and health: report of the Advisory Committee to the Surgeon General of the Public Health Service. Washington, DC: Public Health Service, 1964. (DHEW publication no. (PHS) 64-1103.)