標題: 新程式提供更準確的肺部年齡判斷 [打印本頁] 作者: green 時間: 2009-12-3 11:11 標題: 新程式提供更準確的肺部年齡判斷
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。
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.
