Smoking and lung function

Chronic obstructive pulmonary disease (COPD) is characterized by gradually worsening airflow obstruction interfering with normal breathing, leading to disability and death. Between a quarter and a half of long term smokers develop COPD. Smokers are 13 times more likely to die from COPD than never-smokers, and in recent years more women than men are killed by COPD in the United States.

Relatively quick and simple lung function tests can detect likely lung damage (spirometry) from about age 35 onwards – i.e. after about 20 years of smoking. One of the standard measures is known as “FEV-1” which is the persons maximum total “Forced Expiratory Volume in one second”. To measure this, you take as deep a breath as you can and then blow it as forcefully as you can into a machine, which measures the total volume blown out in one second. For most of us our lung function declines very slowly with age from about age 25, such that it is still pretty good even into our 80s and beyond. Smoking speeds up that decline, leading to disability and death at a younger age, particularly in those susceptible to COPD. Stopping smoking at any age slows down the decline in lung function to that of a never smoker. We also know from the US Lung Health Study that lung function actually improves in the few years immediately following stopping smoking. For people who smoke or have any breathing problems, it makes sense to have your lung function checked. Note that in most cases it will be normal. This should not be interpreted as a sign that you can keep smoking without harming your health. It just means that your lung function hasn’t been impaired yet, and of course says nothing about your risks of cancer, cardiovascular disease etc.

An interesting paper was just published in the BMJ by Dr Gary Parkes and colleagues, showing that smokers who had their lung function measured and explained to them in a specific way, including feedback on their “lung age”, were more likely to have quit smoking a year later than those who had their lung function measured and fed back in the standard way (14% vs 6%). The “lung age” is the age of the average person who has an FEV1 equal to that individual. A typical middle-aged smoker has the lung age of someone 10 years older.

You can access the whole article by Dr Parkes for free at:
http://www.bmj.com/cgi/content/full/bmj.39503.582396.25v1

The single best thing a smoker can do to improve their lung function and live a longer healthier life is to stop smoking.

Labels: cigarette smoking, FEV1, jonathan foulds, lung function, smoking cessation

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