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 COPD is usually caused by smoking, and symptoms include breathing
difficulty, cough, excessive phlegm production and wheezing. Doctors
diagnose it by giving patients drugs to open up the airways and then
having them blow into a large tube connected to a spirometer, a
machine that measures how much air the lungs can hold and how fast
patients can exhale.
In the new study, 50 percent of the current and former smokers who
performed too well on the spirometry test for a COPD diagnosis still
had evidence of airway disease and breathing difficulties that
limited their activities.
“These people may have an airway disease that is similar to COPD
even though they do not meet the current criteria for COPD,” said
lead study author Dr. Prescott Woodruff of the University of
California, San Francisco.
Among the current and former smokers who did have symptoms without a
formal diagnosis, 42 percent of them took drugs known as
bronchodilators to relax the muscles in the lungs and open airways
and 23 percent used steroids to ease inflammation that restricts
airflow.
“We do not know whether these medications will be beneficial,”
Woodruff added by email. “There have been no clinical trials in this
population.”
Globally, more than 65 million people have moderate to severe COPD,
and the condition causes about 5 percent of all deaths, according to
the World Health Organization (WHO).
Most cases are caused by smoking or exposure to second-hand smoke,
but working or cooking around certain toxic dusts, chemicals and
fuels can also contribute, as can frequent respiratory infections
during childhood.
For the study, Woodruff and colleagues reviewed data on respiratory
symptoms and COPD test results for 2,736 current or former smokers
and a control group of people who had never smoked.
The current or former smokers with COPD symptoms but no diagnosis
based on the forced-exhalation test still had the other symptoms at
nearly the same rate as people actually diagnosed with mild to
moderate COPD, researchers report in the New England Journal of
Medicine.
About 65 percent of patients diagnosed with mild to moderate COPD
had symptoms. Only 16 percent of people who never smoked did.
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Current and former smokers with COPD symptoms but no formal
diagnosis also did worse on timed walking tests and lung function
assessments than the current and former smokers without symptoms,
the study found.
The researchers excluded people with asthma or severe obesity from
the analyses, but they cannot say for sure if other underlying
medical conditions contribute to some of the symptoms in
participants. Because the volunteers were not a random sample,
researchers also can’t say that they represent the wider population
of current and former smokers. In fact, it’s also possible that
participants joined the study because they had symptoms, skewing the
results, the study team notes.
Even so, the findings suggest that many people are treated like COPD
patients even though they don’t meet the current definition, Dr.
Leonardo Fabbri of the University of Modena and Reggio Emilia in
Italy noted in an accompanying editorial.
More research is needed to understand these patients because smoking
might cause cardiovascular or metabolic diseases that lead to
breathing problems even when people don’t have test results that
suggest abnormal lung function, Fabbri said by email.
“There are patients with chronic respiratory symptoms even without
spirometric abnormalities confirming COPD, suggesting indeed that we
should introduce the concept of a clinical chronic pulmonary disease
(CPD) induced by smoking in absence of obstruction,” Fabbri said.
SOURCE: http://bit.ly/1Ta1JRI and http://bit.ly/1TdZ3Td New England
Journal of Medicine, online May 12, 2016.
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