Chronic cough eludes treatment in allergy specialty offices

September 29, 2022

5 min read

Key takeaways:

96% of the respondents had academic training in allergy/immunology.
The most common complaints that patients with chronic cough had included social embarrassment, loss of sleep, decreased quality of life and sleep disruption.
Only 20% of respondents said that more than 75% of their patients with chronic cough achieved complete resolution of their symptoms.

Current treatments for chronic cough fail to effectively resolve its symptoms, indicating a need to develop new therapies, according to the results of a survey of allergy specialists published in Annals of Allergy, Asthma & Immunology.

In fact, these specialists indicated that more than 50% of their patients with chronic cough did not rate any of these treatments as "very effective," Bruce Prenner, MD, associate clinical professor in the division of allergy, immunology and rheumatology at the University of California San Diego School of Medicine, and colleagues wrote.

The researchers characterized chronic cough with persistence lasting longer than 8 weeks and an unexplained origin despite completion of therapeutic trials. Allergies, asthma and other underlying conditions all are associated with chronic cough. However, there is no standard treatment due to the heterogeneity of these underlying conditions.

"Chronic cough is more than 8 weeks, and for the majority of these patients, it's years. It's 1 to 5 to 10 to 20 years. It's not something that is transient, unfortunately, and it's triggered by lots of things," Prenner told Healio.

Triggers can include talking, speaking or laughing, Prenner explained. Or they can be external triggers such as temperature changes, chemical irritants or odors.

The survey's distribution and results

The vice president and chief medical officer of a large multisite practice specializing in allergy, asthma and immunology with 45 offices and 61 satellite locations emailed a link to the cross-sectional survey to its allergy specialists.

"The idea was to find out if they understood that chronic cough meant, by definition, more than 8 weeks, as well as what they considered in their differential diagnosis," Prenner said.

With a response rate of 58%, the researchers received answers from 84 of the practice's medical doctors and doctors of osteopathic medicine and 18 of its physician assistants and nurse practitioners.

These respondents had an average age of 47 ± 10.83 years and had been practicing in the specialty for an average of 14.47 ± 10.18 years. Also, 96% of them had academic training in allergy and immunology. In the previous 12 months, 83.3% had treated more than 10 patients with chronic cough.

During each patient's initial assessments, these providers all said, they obtained a medical history and pulmonary function testing. The least frequently used assessments included laboratory tests and computed tomography scans of the sinuses and chest.

"When we asked about their workup, most of them did the appropriate things. Allergists did allergy testing. Some did chest X-rays," Prenner said. "But there were no other real markers. They didn't do exhaled nitric oxide."

According to the survey, 56.8% of the patients were diagnosed with refractory chronic cough, 33.1% were diagnosed with unexplained chronic cough and 10.1% were diagnosed with chronic cough of other type.

Also, 36.4% of patients had experienced symptoms for 3 to 6 months, 25.4% reported having symptoms for 6 to 12 months and 22.2% said their symptoms had lasted 1 to 5 years. Treatment times ranged from less than 1 year (54.2%) to 1 to 5 years (21.9%) to 5 years or longer (23.9%).

Referrals of patients with chronic cough to these allergy specialists came from health care providers (71%), the patients themselves (54.1%) and individuals who were not health care providers such as family or friends (12.2%).

Primary care family physicians (53%), primary care nurse practitioners (50.5%), primary care physician assistants (47.5%) and primary care internists (44.1%) were the most common sources for referrals among health care providers.

"I thought more of these cases would commonly come from the pulmonologist, the [ear, nose and throat (ENT)] doctor or the [gastrointestinal] doctor," Prenner said. "So that was very important information."

Social embarrassment, loss of sleep, decreased quality of life and sleep disruption were the top "very common" complaints among patients. The top patient complaints that the respondents considered "very important" in making a differential diagnosis of chronic cough included nighttime cough, cough frequency, productive cough and daytime/nighttime cough.

When diagnosing chronic cough, the providers most commonly ruled out asthma/eosinophilic bronchitis, upper airway cough syndrome (postnasal drip), gastroesophageal reflux disease and use of angiotensin-converting enzyme (ACE) inhibitors.

The respondents most commonly prescribed anti-reflux treatments, inhaled corticosteroids alone or combined with long-acting beta agonists, short-acting bronchodilators and first-generation antihistamines.

The researchers noted that these therapies also were the most effective treatments, in this same order, although no therapy was rated as "very effective" among more than 50% of the patients. The least prescribed and effective therapies included central- and peripheral-acting antitussives, behavioral therapy, neuromodulators and opioids.

Overall, only 20% of the respondents reported that more than 75% of their patients achieved complete resolution of their symptoms, whereas 55% reported complete resolution of symptoms for less than 50% of their patients.

"The typical anti-cough medications are not effective, and that's why, for example, people are using neuromodulators," Prenner said. "Unfortunately, they have a lot of side effects."

The importance of care

"I've spent all my career looking in people's noses and listening to their chests. But in this particular case, you've got to listen to the people because they can get depressed. They're embarrassed. They have to leave public areas," Prenner said.

"Especially with COVID-19, this puts them in a very embarrassing position. People think 'Oh, they're spreading COVID or viral particles.' So, they really get very personally affected by this and feel like nobody wants to help them," he continued.

These patients get very discouraged, Prenner said, and often stop going to their primary care doctor or to their specialist. Providers themselves have noted how these patients have given up on care.

"When we do studies now looking for patients, it's not uncommon for our colleagues to say that they would love to have us try to help these particular patients," Prenner said.

Based on the persistence of these symptoms and the limited effectiveness of these treatments, the researchers called for the development of additional therapies as well as combinations of therapies to treat chronic cough.

Meanwhile, Prenner encourages his colleagues to watch for the symptoms of chronic cough.

"A history and physical are paramount. Red flags would include a long smoking history, or cough that's productive of thick phlegm," he said. "Weight loss, fever, fatigue — those things should be an alarm and indicate that you have to do a chest CT scan."

Further, Prenner noted that providers should be aware that the use of ACE inhibitors is one of the most common causes of persistent cough.

"Really work with the pulmonologist and come up with a diagnosis," he advised.

Looking ahead, Prenner plans on continuing his research into how providers address chronic cough.

"The next step might be to find out from the allergists, pulmonologists and ENT doctors whether neuromodulators are in their hands and if they are effective — and if they are effective, if there are adverse events," Prenner said.

For more information:

Bruce Prenner, MD, can be reached at prenner@aaamg.com.

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