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作者：Kristina Rebelo  
出處：WebMD醫學新聞

　　November 11, 2009 (加州聖地牙哥) — 根據發表於美國胸腔外科醫師學院年會：2009 CHEST的研究發現，有一種新程式可以取代肺功能量計，用以確認抽菸者的肺部生理年齡。
　　
　　目前使用的摩里斯與湯瑪斯肺部年齡程式(Morris and Thomas lung age formulas)，是根據身高與一秒內用力呼氣容積(forced expiratory volume in 1 second [FEV1])或用力肺活量(forced vital capacity[FVC])的絕對值。主要研究者、加州大學洛杉磯分校名譽教授，目前任職於Harbor UCLA醫學中心、洛杉磯生化研究中心醫學系、呼吸與重症照護生理與醫學科的James E. Hansen醫師表示，使用這些程式，即使病患氣流量減少，也可能被統計歸類為正常值。他表示，這可能會使慢性阻塞性肺部疾病(chronic obstructive pulmonary disease，COPD)患者被誤認是正常。
　　
　　Hansen醫師等人使用「the Third National Health and Nutrition Evaluation Survey (NHANES-3)」這項調查的呼吸量表資料，來自超過50,000名未抽菸的成人，在評估的6個種族/性別組中，建立正常的%FEV1/FEV6值等於「96.9– 0.189×歲– 1.524× FVC (L)」這個程式。
　　
　　研究者在摘要中解釋，因為0.189的倒數大約為5(1/0.189≒5)，我們對NHANES-3調查中，5,800名未曾抽菸者以及3,500名現有抽菸者計算肺部年紀變化時，用5乘以(預測的/實際的) %FEV1/FEV6，因為之前的程式演算自高加索人，我們只對高加索成人比較我們的程式結果和之前的計算結果。
　　
　　Hansen醫師的團隊報告指出，使用%FEV1/FEV6，表示六個種族/性別組中，未曾抽菸者的肺部年紀相當於實際年紀，原本的程式的數值則相當不一定。
　　
　　僅使用目前有抽菸之高加索人的資料時，根據%FEV1/FEV6，肺部平均年齡增加，50歲以上者惡化超過25年，遠高於根據身高和FEV1或FVC所計算的肺部年紀，但是比較有規則可循。
　　
　　在60歲、70歲和80歲時，比較存活之抽菸的高加索人和沒有抽菸的人，男性的肺部年紀增加超過2倍、女性增加超過1.6倍。
　　
　　Hansen醫師向與會聽眾表示，本研究認為，應優先使用%FEV1/FEV6比值這個方法，病患才不會誤認自己的呼吸量表資料在正常範圍內。
　　
　　Hansen醫師在發表時表示，我們發現，NHANES-3調查對於抽菸之影響的代表性不足，因為樣本中沒有人屬於嚴重或極嚴重之COPD(根據慢性阻塞性肺病全球倡議組織的定義)。
　　
　　這個新的計算肺部年紀的方法，發現目前有抽菸的高加索人，各年齡層的肺部年紀都顯著增加。我們可以依據肺部年齡，更正確的將人們分成「正常」或「不正常」，而藉由比較簡單的新程式，醫師甚至可以用心算就知道結果，而不需依賴檢驗室。
　　
　　Hansen醫師的團隊根據測定的% FEV1/FEV6值和平均預測值的改變，將未曾抽菸者和現有抽菸者進行分類，之後根據每10歲年紀製圖。
　　
　　從30到80歲時，受到抽菸顯著影響的抽菸者都減少，研究者發現，多數抽菸者(20-29歲)的% FEV1/FEV6值低於平均預測值。
　　
　　Hansen醫師表示，% FEV1/FEV6值低於平均預測值的抽菸者百分比，隨著每一年齡層增加，特別是50歲以上者，告知病患其肺部年紀增加有助於戒菸，這是讓病患參與肺部復健計畫的一大動機。
　　
　　在發表後的訪問中，Hansen醫師向Medscape Pulmonary Medicine表示，病患會因為他們覺得很好，認為他們實際上也很好。
　　
　　他表示，他們的狀況可能處於下坡而不自知，首要之務在告訴病患戒菸，這是醫師們的責任。
　　
　　Hansen醫師結論表示，相較於後續發生的循環系統或其他系統傷害，呼吸系統傷害的檢查比較簡單且便宜。
　　
　　會議主持人、耶魯醫學院副教授、West Haven VA醫學中心主治醫師Carolyn L. Rochester受Medscape Pulmonary Medicine之邀發表評論。
　　
　　她表示，我認為這是值得後續研究的有趣新觀念，但是我們得耗費相當多時間讓健康照護提供者接受這個觀念。它可能很有用，但事實上，可能難以取代佔使用首位的呼吸量表，且支持FEV1/FEV6只是理論上的一個好觀念，但是，別著急，我們只需要一個可以明確地讓人們戒菸的研究。
　　
　　本研究未接受資助。Hansen醫師和 Rochester醫師皆宣告沒有相關財務關係。
　　
　　美國胸腔外科醫師學院年會：2009 CHEST：摘要7896。發表於2009年11月3日。


New Formula Offers a More Accurate Gauge of Lung Age

By Kristina Rebelo
Medscape Medical News

November 11, 2009 (San Diego, California) — Spirometry should be replaced with a new formula to determine physiological lung age in smokers, according to study findings presented here at CHEST 2009: American College of Chest Physicians Annual Meeting.

The Morris and Thomas lung age formulas currently used are based on absolute values of height and forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC). Even patients with reduced airflow measurements can be pegged as being statistically within normal values using these formulas, asserted principal investigator James E. Hansen, MD, professor emeritus, University of California at Los Angeles, currently at the Division of Respiratory and Critical Care Physiology and Medicine, Department of Medicine, Los Angeles Biomedical Institute at Harbor UCLA Medical Center in Torrance. This gives patients with chronic obstructive pulmonary disease (COPD) a false sense of normalcy, he said.

Dr. Hansen and colleagues used spirometric data from the Third National Health and Nutrition Evaluation Survey (NHANES-3), collected from more than 50,000 adult never-smokers, to establish that the normally distributed %FEV1/FEV6 is 96.9?– 0.189?× years?– 1.524?× FVC (L) in all 6 ethnic/sex groups evaluated.

"Since the reciprocal of 0.189 approximates 5, we calculated changes in lung age years using 5 times (predicted/actual) %FEV1/FEV6 for 5800 NHANES-3 never-smokers and 3500 current smokers," the researchers explained in their abstract. "Since the earlier formulas were derived from Caucasians, we compared results of their and our formulas in only Caucasian adults."

"Using %FEV1/FEV6, mean lung ages of 6 ethnic/gender adult groups of never-smokers closely approximated actual lung ages, while values using the earlier formulas were erratic," Dr. Hansen's team reported.

"Using only the current-smoking Caucasian population, mean increases in lung age, based on %FEV1/FEV6, progressed to over 25 years by ages 50 and above, much higher but less erratic than using lung ages based on height and FEV1 or FVC."

"In comparing surviving Caucasian current-smokers with never-smokers in the sixth, seventh, and eighth decades, over twice as many men and 1.6 times as many women had increased lung age."

This study suggests that the preferred method is to use the ratio of %FEV1/FEV6, so that patients are not being misled into believing that their spirometry data are within normal ranges, Dr. Hansen told meeting attendees.

"We found that the NHANES-3 underrepresents the effects of smoking because no one in the sample had severe or very severe COPD by [Global Initiative for Chronic Obstructive Lung Disease] definitions," Dr. Hansen said during his presentation.

"The suggested new way of calculating lung age of Caucasian current smokers would have all decades of smokers with "significantly increased lung age. We can do better in calling people 'normal' or 'abnormal' when it comes to lung age. With this easier formula, the physician can even do it in [his or her] head — it isn't dependent on lab calculations."

Dr. Hansen's team divided never-smokers and current smokers into categories by determining % difference of FEV1/FEV6 actual from mean predicted values and then plotting by decades of age.

Smokers that were most affected by smoking were eliminated in each decade, from the third to the eighth. The researchers found that most of the smokers (20 to 29 years) have %FEV1/FEV6 values below mean predicted.

"That percentage of smokers with %FEV1/FEV6 values below mean predicted increases with each decade of life, especially by age 50 or older," said Dr. Hansen. "Informing the patient of this increased age of their lung is an enticement to stop smoking. It really is a big motivator to get patients into a pulmonary rehab program."

During an interview after his presentation, Dr. Hansen told Medscape Pulmonary Medicine that patients believe that because they feel fine, they are fine.

"They're probably on a downhill slope already and they don't know it," he said. "The first thing to do is to tell a patient to stop smoking. That's a doctor's responsibility."

Dr. Hansen concluded that "damage to the respiratory system is easier and cheaper to identify early on than damage to the circulatory and other systems down the road."

Commenting on the session for Medscape Pulmonary Medicine was moderator Carolyn L. Rochester, MD, associate professor, Yale School of Medicine, New Haven, Connecticut, and attending physician at West Haven VA Medical Center.

She said: "I think it's an interesting new idea that we should explore further, but we have a hard enough time to get the masses of healthcare providers to buy into the idea. It could be very useful, but as it is, it's hard to get spirometry in the first place and the issue of backing it up further with FEV1/FEV6 is a nice idea in theory, but before we go crazy with it, we need a study to see if telling people in language is enough to get people to quit smoking."

The study received no funding. Dr. Hansen and Dr. Rochester have disclosed no relevant financial relationships.

CHEST 2009: American College of Chest Physicians Annual Meeting: Abstract 7896. Presented November?3, 2009.