The intensity of cough increases significantly before death, although less markedly than for dyspnoea ( 9). The severity of cough in IPF is greater than in other types of interstitial lung disease (ILD) ( 6– 8). A minority of patients have a chesty cough from the onset of disease. Cough Description and ImpactsĬough due to IPF is typically described as dry or non-productive and refractory to antitussive therapy. Despite this, further evidence is required to conclusively demonstrate the relationship between cough and disease progression in patients with IPF. In a cohort of 242 patients with IPF, the presence of cough was an independent predictor of disease progression, defined as a 15% decline in the diffusing capacity of the lungs for carbon monoxide, a 10% decline in forced vital capacity, lung transplantation, or all-cause mortality ( 2). Increased cough frequency measured by mean coughs per hour have been associated with reduced exercise tolerance and higher serum levels of Krebs von den Lungen 6 molecule ( 5), a marker of alveolar epithelial cell injury currently under evaluation as a prognostic biomarker in IPF. ![]() Possible mechanisms include nicotine-induced inhibition of C fibers, changes in mucociliary clearance or desensitization of cough receptors in airway epithelium ( 4).Ĭough is more prevalent in patients with advanced IPF ( 2). Smokers have reduced cough counts in response to capsaicin provocation when compared to non-smokers. Unexpectedly, smoking history is the strongest predictor of cough in IPF, with current or ex-smokers less likely to report cough ( 2). Female gender and never-smoking status are associated with increased cough frequency in patients with IPF measured objectively by 24-h cough recording ( 3). Cough is often the first symptom and may precede diagnosis by months to years. Cough Characteristics Epidemiology and DemographicsĬough and dyspnoea are the two most common symptoms described in patients with IPF, with up to 80% experiencing chronic cough ( 2). Along with accurate assessment of cough severity, improved understanding of the pathophysiological mechanisms and contributors to cough, and development of evidence-based management are vital to improve quality of life in patients with IPF. In the absence of a gold standard measuring cough intensity, or the force of cough, it has been assessed objectively using physiological measures such as expiratory flow in research settings, and subjectively using patient reported instruments for its impact. Cough frequency is an objective measurable index, which is commonly expressed as absolute cough counts and number of coughs per hour. The severity of cough encompasses its frequency, intensity, and impact to patients' lives ( 1). Cough is a common symptom, often occurring years prior to diagnosis, contributing to poor prognosis and reduced quality of life. It is associated with significant morbidity and mortality, with progressive worsening of respiratory symptoms over time. Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing idiopathic interstitial pneumonia, most prevalent after the 6th decade of life. This review provides an update on the clinical characteristics, pathophysiology, and measurement of chronic cough in patients with IPF and summarizes recent developments in non-pharmacological and pharmacological therapies. There is a renewed emphasis on measuring cough in IPF, with clinical trials of novel and repurposed therapies for chronic cough emerging in this population. Modifiable comorbidities can also induce cough in patients with IPF. The pathophysiology is likely multifactorial and includes alterations in mucous production and clearance, architectural distortion, and increased cough reflex sensitivity, suggesting a role for targeted therapies and multidisciplinary treatment. Although not fully understood, recent gains in understanding the pathophysiology of chronic cough in IPF have been made. It is often the first symptom and is associated with reduced quality of life, increased rates of depression and anxiety, more severe physiological impairment, and disease progression. 5Central Clinical School, Monash University, Melbourne, VIC, AustraliaĬhronic cough is experienced by most patients with idiopathic pulmonary fibrosis (IPF). ![]() ![]() 4Department of Physiotherapy, Alfred Health, Melbourne, VIC, Australia. ![]()
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