Causes of persistent cough
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Causes of Persistent Cough: An Overview
Persistent cough, defined as a cough lasting more than eight weeks, is a common symptom that can significantly impact quality of life. Understanding its causes is crucial for effective diagnosis and treatment. This article synthesizes findings from multiple studies to highlight the primary causes of persistent cough in both adults and children.
Cough-Variant Asthma and Cough-Predominant Asthma
Cough-variant asthma (CVA) and cough-predominant asthma (CPA) are leading causes of persistent cough. A multicenter study in Japan found that CVA accounted for 42.2% of prolonged cough cases, while CPA was responsible for 28.4%. These conditions are characterized by a chronic cough without the typical wheezing associated with asthma, making them challenging to diagnose without specific tests.
Upper Airway Cough Syndrome and Postnasal Drip
Upper airway cough syndrome (UACS), previously known as postnasal drip syndrome, is another prevalent cause. Studies indicate that UACS is responsible for a significant portion of chronic cough cases, often in conjunction with other conditions like asthma . The syndrome involves mucus dripping down the back of the throat, triggering the cough reflex.
Gastroesophageal Reflux Disease (GERD)
Gastroesophageal reflux disease (GERD) is a notable contributor to persistent cough. GERD-related cough occurs due to the backflow of stomach acids irritating the esophagus and respiratory tract. Research shows that GERD is a common cause, with one study highlighting it as a primary predictor for the persistence of cough over a 12-month period .
Chronic Bronchitis and Chronic Obstructive Pulmonary Disease (COPD)
Chronic bronchitis and chronic obstructive pulmonary disease (COPD) are also significant causes. Chronic bronchitis, characterized by long-term inflammation of the bronchi, leads to a productive cough. COPD, which includes chronic bronchitis and emphysema, is marked by airflow obstruction and persistent respiratory symptoms .
Post-Infectious Cough
Post-infectious cough can persist after the resolution of an acute respiratory infection. This type of cough is thought to result from cough hypersensitivity induced by the initial infection. The cough serves as a protective mechanism but can become excessive and chronic.
Environmental and Lifestyle Factors
Environmental factors such as exposure to cigarette smoke and air pollution are well-documented causes of chronic cough. Smoking, in particular, is strongly associated with persistent productive cough . Additionally, occupational exposures and environmental pollutants can exacerbate or trigger chronic cough conditions.
Pediatric Considerations
In children, the most common causes of persistent cough include upper airway cough syndrome, cough-variant asthma, and prolonged bacterial bronchitis. These conditions require an integrated diagnostic approach to ensure effective treatment .
Conclusion
Persistent cough is a multifaceted symptom with various underlying causes. Accurate diagnosis is essential for effective treatment, which often involves addressing multiple contributing factors. Common causes include cough-variant asthma, upper airway cough syndrome, gastroesophageal reflux disease, chronic bronchitis, and environmental factors. Understanding these causes can guide healthcare providers in managing and alleviating this challenging condition.
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