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Tuesday 25th June 2019

Why asthma drugs don't work for some

10th January 2012

Researchers have found large numbers of patients with different types of asthma, requiring very different treatments, according to a recent US study.


Nearly 50% of patients whose asthma symptoms are moderate to mild may have a different type of disease altogether.

Study author John Fahy, a research director at the University of California in San Fransisco, said researchers were beginning to understand that different 'flavours' of asthma probably had different molecular mechanisms.

Asthma is a type of airway inflammation, and is classified as a chronic disease, often involving what is known as eosinophilic airway inflammation.

Eosinophils are a type of white blood cell that can fight infections, and the researchers found that 47% of all asthma patients actually did not have a problem with their eosinophils.

Instead, the tightened muscles around the airways, which cause wheezing and coughing and can be life-threatening, get enflamed for different reasons, many of which doctors still do not fully understand.

Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York City, said that researchers could not guarantee that the current treatment regimen actually worked, even in mild asthma cases.

He said that the finding that about half of the asthma patients did not have a problem with eosinophils was surprising, and that doctors should ask patients if they tended to cough up a lot of phlegm.

The researchers measured the white blood cell count of asthma patients' phlegm, and found that only half had eosinophilia.

The researchers then tested the way the study subjects' asthma responded to anti-inflammatory drugs and bronchodilators.

In those tests, people who did not have eosinophilia did not respond at all to treatment.

Fahy said he believed that, among the 50% who didn't respond to standard treatment, there were probably further subtypes.

He said the finding reinforced the idea that asthma was a multi-type disease.

Horovitz said the number of people who did not have eosinophilia in their phlegm was higher than he thought, and that people who produced a lot of phlegm would tend to respond to corticosteroids.

He said that the cascade process, by which inflamed airways become more and more swollen, had been well-studied.

Fahy said that the test used to determine whether or not study subjects might respond to traditional treatments was not easy to administer in clinical practice.


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