禁煙した者の心疾患リスク低下はこれまで推定されたよりも速い（Abstract: 18709）

過去の喫煙者の一部は心不全および心血管死のリスクが15年未満で軽減する可能性がある

Some former smokers may reduce their risk of heart failure and cardiovascular death in less than 15 years

65歳超の煙草喫煙者は禁煙することにより、心血管疾患死のリスクがこれまで報告されていたよりも速く喫煙歴のない者と同程度まで低下する可能性があるとの研究結果が2013年American Heart Association学会で発表された。研究者らは禁煙してから15年以下の853人と、全く喫煙歴のない2,557人を比較した。過去の喫煙者853 人のうち319人は喫煙本数が32パック／年未満であった。スタディの結果、喫煙本数が32パック／年未満―1日3.2パック（1パック20本）を10年以下、または1日1箱未満を30年―で、禁煙してから15年以下の高齢者は心不全発症または心不全、心筋梗塞、脳卒中により死亡するリスクが全く喫煙歴のない者と同程度まで低下した。スタディ対象者の多くは15年未満（中央値8年）でリスクを低下させることができた。喫煙者はそれでも、心血管系疾患以外のがん、慢性閉塞性肺疾患および肺気腫などにより死亡するリスクが高かった。

Cigarette smokers who are over 65 years of age may be able to lower their risk of cardiovascular disease-related deaths to the level of never-smokers when they quit faster than previously reported, according to research presented at the American Heart Association's Scientific Sessions 2013.

A study showed that older people who smoked less than 32 "pack years" – 3.2 packs (20 cigarettes per pack) a day for no more than 10 years or less than one pack a day for 30 years – and gave up smoking 15 or fewer years ago lowered their risks of developing heart failure or dying from heart failure, myocardial infarction and strokes to the same level as those who had never smoked.

Previous research showed it may take up to 15 years or more of abstinence for smokers to reach similar cardiovascular death risks as people who never smoke. But many of the people in the study were able to reduce their risk in less than 15 years (median eight years).

"It's good news," said Ali Ahmed, M.D., M.P.H., senior researcher and professor of cardiovascular disease at the University of Alabama at Birmingham's School of Medicine. "Now there's a chance for even less of a waiting period to get a cleaner bill of cardiovascular health."

Ahmed and his colleagues analyzed 13 years of medical information compiled in the Cardiovascular Health Study, started in 1989 and funded by the National Heart, Lung, and Blood Institute. They compared 853 people who quit smoking 15 or fewer years before with 2,557 people who had never smoked.

Of the 853 former smokers, 319 had smoked less than 32 pack years. Pack years are determined by multiplying the cigarette packs smoked per day times the number of years a person has smoked. All participants were over age 65 years of age. Results were adjusted for age, gender and race.

Smokers who smoked less than 32 pack years but quit 15 or fewer years ago still had higher risks of dying from causes unrelated to cardiovascular health, such as cancer, chronic obstructive pulmonary disease and emphysema. Former smokers who smoked more than 32 pack years had higher risks of dying from any health condition.

"Smoking is the most preventable cause of early death— if you smoke, quit and quit early!" Ahmed said.

Co-authors are Amiya Ahmed, Charity Morgan, Ph.D.; Gregg Fonarow, M.D.; Sumanth Prabhu, M.D.; Vera Bittner, M.D., M.S.P.H.; Kanan Patel, M.B.B.S., M.P.H.; Prakash Deedwania, M.D.; Gerasimos Filippatos, M.D., Ph.D.; Stefan Anker, M.D., Ph.D.; and Wilbert Aronow, M.D.