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Blood Tests May Predict COPD Flare-Ups
Signs of chronic inflammation in the blood linked to faster deterioration of lung function
Tuesday, June 11, 2013
In addition to the slow, steady deterioration in lung function caused by COPD, patients can have sudden, distressing flare-ups. These so-called "exacerbations" are periods of worsening breathing problems that are typically triggered by infections or air pollution.
Patients who experience frequent flare-ups decline more quickly than those who do not; they also tend to have worse quality of life and poorer survival rates than those whose conditions are more stable, according to background information in the study.
Preventing flare-ups is a major goal of COPD treatment, but these episodes can be difficult to predict.
In a study of more than 61,000 people in Denmark, researchers found that COPD patients who had increased levels of certain proteins and cells in their blood were at greater risk for frequent flare-ups.
These particular proteins and cells -- C-reactive protein, fibrinogen and leukocytes -- increase in response to infections, tissue damage and inflammation.
People with higher levels of all three of these "markers" were more likely to experience frequent flare-ups than those with normal levels. That was true regardless of the stage or severity of their COPD.
But the risk was especially pronounced for patients in the study with the worst breathing problems. Among patients who had the highest grade of COPD symptoms, 24 percent with no elevated markers had frequent flare-ups compared to 62 percent of those who had high levels of all three markers.
Patients with frequent exacerbations had two or more flare-ups each year they were followed for the study.
The study is published in the June 12 issue of the Journal of the American Medical Association.
According to Dr. Elizabeth Regan, who is studying the genetics of COPD at National Jewish Health in Denver, the researchers "give compelling evidence that those are useful tests." Regan was not involved with the study.
"These are tests that are readily available. The practicing physician kind of has them at their fingertips. They're not unusual, they're not high-risk," said Regan. "If I were seeing patients, I'd be strongly attracted to doing it."
The price of each test varies, but in general, they're inexpensive, ranging between $10 and $40. Insurance often covers the cost. The only trouble with doing the tests now, Regan said, is that doctors still don't know exactly how to use the information.
"While these tests look like they're strong predictors, we don't have the next piece of this clearly in place," she noted.
The study wasn't able to prove that inflammation causes COPD exacerbations, or that lowering inflammation with medications could head off future flare-ups, Regan explained.
Other studies currently underway are testing whether antibiotics or newer medications can prevent such attacks, she noted.
Until more is known, the researchers say there is still one good reason for COPD patients to get the blood tests.
"Many patients with COPD aren't very adherent to their inhalation medication. Patients don't like to be sick, so they think 'it's doing well now, so let me stop,'" said study author Dr. Borge Nordestgaard, a clinical professor in the department of diagnostic sciences at the University of Copenhagen in Denmark.
"But if you're one of these patients with high biomarkers, then you should be even better at taking your daily inhalation medication," he said. "That's the best advice at present."
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