Chronic Lung Disease More Widespread Than First Thought And Rising, New Study

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Main Category: Respiratory / Asthma
Also Included In: Public Health
Article Date: 31 Aug 2007 - 7:00 PDT

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A new study by US researchers suggests that the global rate of chronic lung disease, called chronic obstructive pulmonary disease (COPD), is higher than previous estimates have suggested and is growing steadily as the world's population gets older. The authors conclude that cost effective prevention and treatment is the best way to stem the rising tide of this disease and its burden on health care.

Experts have welcomed the study and say it has highlighted a growing global health problem.

The study is published in the 1st September issue of The Lancet and is the work of Dr David M Mannino, Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, Lexington, Kentucky, and Dr A Sonia Buist, Department of Medicine, Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon.

Mannino and Buist found that cigarette smoking is the biggest risk factor for COPD, followed by being exposed to pollution both in and out of doors. Other illnesses and work related hazards are also significant risk factors.

Buist, who heads up the Pulmonary and Critical Care Medicine division of Oregon Health and Science University, said that COPD is under-diagnosed and under- treated. It is more common than previous estimates have suggested; there is a big difference between the reality and the public health perception, she said.

COPD is a collective term for a range of chronic lung diseases that limit airflow in the lungs. It is the fifth leading cause of death throughout the globe.

According to the World Health Organization, the more familiar terms 'chronic bronchitis' and 'emphysema' are no longer used because they are now included in the COPD diagnosis.

Symptoms of COPD include feeling breathless, as if one can't get enough air, excessive sputum, and a chronic cough. As the WHO explains, COPD is not "simply a smoker's cough, but an under-diagnosed, life threatening lung disease that may progressively lead to death".

The WHO estimates that 80 million people throughout the world have moderate to severe COPD and the number who died from the disease in 2005 was near 3 million. They predict that by 2030 it will be the fourth leading cause of death in the world.

"COPD is a cumulative response of the lungs to the burden of all that's breathed in over a lifetime," said Buist. This explains why the prevalence rises as the population ages.

Mannino and Buist studied medical information (including results from spirometry tests that measure breathing ability) on 9,425 people aged 40 and over from 12 different countries.

They found that:

• The overall prevalence of COPD was 10.1 per cent.
• This compares with previous estimates from another study that put the prevalence at 4.3 per cent.
• Among men the prevalence of COPD was 11.8 per cent.
• Among women it was 8.5 per cent.
• Differences in smoking behaviour probably explains the difference in COPD rates between men and women.
• The figures varied widely across different countries.
• South Africa had the highest proportion of people with COPD: 22.2 per cent of men and 16.7 per cent of women.
• Hanover in Germany had the lowest prevalence: 8.6 per cent of men and 3.7 per cent of women.
• In the US, the overall prevalence of serious COPD is 10.1 per cent.
• The risk of COPD is nearly doubled for every 10 years of age above 40.
• Smoking has a similar large effect on risk.

Buist said that:

"This worldwide study showed higher levels and more advanced staging of spirometrically confirmed COPD than have typically been reported."

There is no cure for COPD and the advice of the authors is that people can reduce their COPD risk by not smoking and avoiding atmospheres that contain pollutants and smoke, and if you have to work with pollution then wear a mask or other form of protection.

There is some room for optimism though. We now know a lot more about how to prevent and treat COPD. As the authors explained in their summary, scientific understanding of COPD has grown in a number of areas recently. For instance we know more about how:

• Other diseases affect COPD (comorbidity),
• COPD affects people with different genetic backgrounds (COPD phenotypes), and
• COPD affects health in ways other than lung function.

"Global burden of COPD: risk factors, prevalence, and future trends."
David M Mannino, A Sonia Buist.
The Lancet 2007; 370:765-773
Volume 370, Number 9589, 1 September 2007
DOI:10.1016/S0140-6736(07)61380-4

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Written by: Catharine Paddock
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