Solving mysterious chronic cough cases

Many factors need to be taken into account when diagnosing coughs that last for eight or more weeks, including how symptoms and possible causes can overlap.

Treating chronic cough involves tackling a multifactorial disease in two-thirds of cases, so take time to understand the whole picture, said Kenneth W. Altman, MD, PhD, at his talk on the subject Thursday.

“[Chronic cough] is a mystery,” said Dr. Altman, professor and vice chair for clinical affairs and director of the Institute for Voice and Swallowing at Baylor College of Medicine in Houston. “The longer you take to get to the bottom of it, the longer it's going to take to improve their quality of life—and the more it's going to cost them in their life functions.”

He put some numbers on the prevalence of chronic cough. “It's really a worldwide problem,” with a prevalence of 10% to 12% of the global population at any given time. In 2013, U.S. sales of over-the-counter cough and cold remedies totaled $6.8 billion. Chronic cough is the third most common reason for ambulatory care visits, after general medical exams and nonspecific progress visits.

Given those numbers, not all affected patients can receive specialist care. “If you feel like we [otolaryngologists] should be involved in chronic cough, there's really a wholly unmet need,” he said. “It's more important for internal medicine doctors to be empowered in the front lines of caring for cough.”

Chronic coughs are those that continue for more than eight weeks, or in the case of one patient, more than 30 years. Dr. Altman recalled this patient, a 71-year-old man who had been chief financial officer for an oil company (but with no field exposure to chemicals). He had a lifelong history of allergies and had been treated as a child with shots. His main symptom was longstanding, persisting morning nasal congestion with nonproductive cough after eating a small amount of food. His medicines included an older angiotensin-converting-enzyme (ACE) inhibitor, ramipril, that he had taken for 30 years.

“How long has the coughing been going on?” Dr. Altman asked the patient, who replied, “Thirty years.”

The case illustrates the many factors that need to be taken into account in cough diagnosis, including how symptoms and possible causes can overlap. In this case, Dr. Altman said he had to distinguish among possible causes such as the ACE inhibitor, allergic rhinitis, postcibal reflux, and microaspiration.

In general, Dr. Altman said, the most common single causes of cough are tobacco use, post-nasal drip, gastroesophageal reflux disease/laryngopharyngeal reflux, bronchitis, reactive airway disease, and the use of ACE inhibitors. But there's often more than one cause, he continued. “If you look at all these patients with chronic cough, two-thirds are multifactorial.”

Given the multifactorial natures, in cases where empiric treatment has failed, he prefers to conduct diagnostic testing “rather than shooting from the hip and throwing medicine at them.” He later added, “I'm not trying to save any money here on the up-front testing.”

He recommended that internists follow guidelines last updated in 2014, “Overview to the Diagnosis and Management of Cough,” published in CHEST. In these guidelines, systematic reviews inform recommendations on 42 clinically important topics, including research. A panel of 55 worldwide experts in 21 disciplines strives to develop, publish, and update them according to a “living guidelines model.”

In the video above, Dr. Altman emphasized the importance of the published guidelines in distinguishing causes and symptoms of chronic cough.

First, ask about lifestyle and medical history when assessing patients, including profession, personal life, exposures, and smoking, Dr. Altman advised. Then, per the 2014 guidelines, order a chest X-ray for a chronic cough lasting longer than two months. Sometimes the findings are unexpected: “I found tuberculosis in one patient,” he said. Then, take patients off ACE inhibitors. “If there's one message I leave you with today, that's the most important one.”

For rhinitis, try empiric therapies such as nasal sprays and antibiotics—but not for too long, Dr. Altman said. Testing can include allergy assessments and sinus CT scans. For allergy testing, he does a serology on the 18 most common allergens in Texas.

To manage cough of pulmonary etiology, empiric therapy includes bronchodilators and steroids. Objective testing includes pulmonary function testing, a methacholine challenge, chest CT, and bronchoscopy.

For esophagus-related coughing, empiric therapy includes proton-pump inhibitors, management through diet and lifestyle, alginates, and motility agents. If these don't work, conduct a barium swallow or 24-hour pH tests, among others.

Cough may also have neurologic causes. Empiric therapy includes pharmacologic suppression, respiratory retraining, and laryngeal desensitization. Objective testing includes an MRI of the brain, modified barium swallow, and laryngeal electromyography.

The latest evidence shows that gabapentin can be used for neurologic coughs, Dr. Altman added. Also, behavioral suppression can retrain patients. Speech therapists teach methods such as dry swallow, use of ice water, conscious awareness of triggers, and early recognition and avoidance of cough.

“I don't like to spend too much time on empiric therapy if it's not working. I like to jump to the bottom of it so our patients are not those that come in six years later, or 20 years later, living with this chronic cough,” he said.