Health Woes Not Always to Blame for Chronic Cough
FRIDAY April 18, 2008 -- The widespread belief that chronic cough is only connected to other conditions is hampering the development of new treatments, according to a paper by U.K. researchers.
It's one of two studies on chronic cough published in this week's issue of The Lancet. Both papers are by the same authors: Kian Fan Chung of the National Heart and Lung Institute, Imperial College London; and Ian Pavord, of the University Hospitals of Leicester NHS Trust.
In the first paper, the authors provided information on chronic cough, which is defined as a cough lasting longer than eight weeks. The condition, which affects 9 percent to 33 percent of the population in many areas of Europe and the United States, is often associated with cigarette smoking. Compared to non-smokers or ex-smokers, smokers are three times more likely to have chronic cough.
Acute infections, chronic infections, airway diseases, tumors, foreign bodies, cardiovascular diseases, and heart drugs such as ACE inhibitors are among the other causes of chronic cough, which is one of the most common reasons why people see a family doctor. Chronic cough accounts for 10 percent to 38 percent of respiratory outpatient practice in the United States, the experts wrote.
"Doctors should always work towards a clear diagnosis, considering common and rare illnesses. In some patients, no cause is identified, leading to the diagnosis of idiopathic cough," they noted.
They said the many causes of chronic cough, plus the cough reflex itself, could cause inflammation or tissue remodeling. This could cause an enhanced cough reflex, which could maintain chronic cough through a positive feedback process.
"Effective control of cough requires not only controlling the disease causing the cough but also desensitization of cough pathways," the authors concluded.
The second paper focused on management of chronic cough. Much of the available evidence suggests that isolated chronic cough is usually caused by asthma, gastroesophageal reflux disease, or upper airway conditions and can be cured by treating these conditions. But the authors questioned this belief.
"There is increasing recognition that satisfactory control of chronic cough is not achieved in a substantial number of patients seen in secondary care. Moreover, there is concern that perpetuation of the belief that chronic cough is solely due to the effects of comorbid conditions is inhibiting research into the pathophysiology of an abnormally heightened cough reflex, and jeopardizing development of improved treatments," they noted.
"Large-scale recognition is needed of the substantial numbers of patients whose chronic cough cannot be diagnosed or controlled with present investigation and treatment protocols," the two experts concluded. "Hence, we need more research and better treatments. Recognition of this large unmet need and the development of a number of well validated techniques to measure chronic cough can only help in this effort."
Posted: April 2008