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Nearly 40% of Chronic Cough Cases Remain Unexplained After Extensive Testing, Therapy


Despite receiving specialty referrals and multiple prescriptions medications, nearly 40% of patients with an unexplained chronic cough are not given a proper diagnosis.

Despite many patients receiving medical evaluations, specialty referrals, and prescription therapeutics, almost 40% of chronic cough cases remained unexplained, according to a poster presented at the American Academy of Allergy, Asthma & Immunology 2021 Annual Meeting.

Chronic cough is defined as a cough lasting more than 8 weeks. Unexplained chronic cough (UCC) is a chronic cough subset where an apparent cause for symptoms cannot be found after thorough analysis. It is estimated that UCC affects between 5% and 10% of American adults.

Despite an identified etiology, health care professionals pursue medication trials and imaging tests until a diagnosis is determined, which can put a large burden on the health care system and patients.

Primary care providers are usually the first health care specialists to evaluate UCC. However, it’s not clear how common UCC occurs in the primary care population.

Investigators set out to characterize the prevalence of new onset chronic cough presented to primary care clinics and identify those patients who were classified as having UCC.

The observational, retrospective study incorporated real-world data from the Northwestern Medicine Enterprise Data Warehouse electronic health record repository on adult patients visiting an outpatient primary care clinic within a tertiary center between 2015 and 2018. Patient charts were examined for 3.5 years from initial primary care physician visit.

During the study period, 122 patients visited a primary care physician. Of those patients, 98 were identified to be the final chronic cough cohort. Patients in this cohort had a mean age of 61.1 (15.3) years, were mostly White (74.5%), and were mostly comprised of women (67%).

Sixty-four patients received a referral to a specialist, 28.1% (n= 18) of which were for patients with UCC. Forty-five (45.9%) patients within the chronic cough cohort were referred to 1 or more specialists. The most common specialties referred to were pulmonology (31.6%), allergy and immunology (13.2%), otolaryngology (12.2%), and gastroenterology (8.2%).

The most common medications prescribed to patients with UCC were intranasal steroid or azelastine nasal spray (89.2%), antibiotics (70.3%), oral steroid (62.2%), acid reflux medication (59.5%), and inhaled corticosteroid either alone or in combination with a long-acting beta agonist (59.5%).

After 3.5 years after the first primary care visit, 61 (62.2%) patients were determined to have a chronic cough and 37 (37.8%) had UCC with no clear etiology.

Twenty-seven percent (n = 10) of patients with UCC who saw a specialist still did not have an apparent reason for their cough, whereas 62.2% (n = 61) eventually received a diagnosis. Of the patients who received an official diagnosis, 39.3% (n = 24) had a multifactorial cough that had more than 1 etiology.

The most common diagnoses found were gastroesophageal reflux disease (41.0%), rhinitis (39.3%), asthma (23.0%), and chronic obstructive pulmonary disease (6.6%).

“Further clinical characterization will inform future research and treatment directions for chronic cough,” wrote the investigators.


Patel AK, Vu T-HT, Guo A, Sinard RN, Peters AT. Characterizing new onset chronic cough in primary care clinics. Presented at the American Academy of Allergy, Asthma & Immunology 2021 Annual Meeting, February 26-March 1, 2021; Poster 190.

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