Unexplained Cough in the Adult
Division of Pulmonary, Allergy, and Critical Care Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA. Otolaryngologic Clinics of North America
(Impact Factor: 1.49).
02/2010; 43(1):167-80, xi-xii. DOI: 10.1016/j.otc.2009.11.009
Unexplained cough is a diagnosis of exclusion that should not be made until a thorough validated diagnostic evaluation is performed, specific and appropriate validated treatments have been tried and failed, and uncommon causes have been ruled out. When chronic cough remains troublesome after the initial work up, determine that a protocol has been used that has been shown to lead to successful results. If such a protocol has been used, next consider whether or not pitfalls in management have been avoided. If they have been, the frequency of truly unexplained chronic cough usually should not exceed 10%. While patients with truly unexplained coughs have an overly sensitive cough reflex, the mere presence of an overly sensitive cough reflex does not by itself explain why they do not get better, because most patients with chronic cough, even those who respond to treatment and get better, have demonstrable heightened cough sensitivity. Management options include referral to a cough clinic with interdisciplinary expertise, speech therapy, and self-limited trials of drugs, preferentially with those shown to be effective in randomized, double-blind placebo-controlled trials in patients with unexplained chronic cough.
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ABSTRACT: Chronic cough that cannot be explained after basic evaluation is a common reason for patients to be referred to respiratory outpatient clinics. Asthma, gastroesophageal reflux, and upper airway disorders frequently coexist with chronic cough. There is some controversy as to whether these conditions are causes or aggravants of cough. Heightened cough reflex sensitivity is an important feature in most patients. There is good evidence that it is reversible when associated with upper respiratory tract infection, angiotensin-converting enzyme inhibitor medications, and chronic cough associated with eosinophilic airway inflammation. In many patients, heightened cough reflex sensitivity is persistent and their cough is unexplained. There are few therapeutic options for patients with unexplained chronic cough. There is a pressing need to understand the genetic, molecular, and physiological basis of unexplained chronic cough and to develop novel antitussive drugs that down-regulate cough reflex sensitivity.
American Journal of Respiratory and Critical Care Medicine 12/2010; 183(6):708-15. DOI:10.1164/rccm.201007-1017CI · 13.00 Impact Factor
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ABSTRACT: Objectives/Hypothesis: To evaluate characteristics of patients with chronic cough referred to otolaryngology, efficacy of common therapies, and the yield of common studies used to evaluate cause of chronic cough. Study Design: Retrospective review. Methods: Patients were identified as being referred for cough between 2005 and 2010. Initial consultation and clinical encounters were reviewed and diagnostic studies/therapies recorded. Findings on diagnostic studies were noted if they aided in treatment. Response to therapies was determined by reviewing clinical encounter documentation and therapies were rated: no response, partial response, or complete response. Results: 132 patients were included in the study. The average age was 57 years and 68% were women. 12% were currently on an ACE-inhibitor and 4% were actively using tobacco at time of presentation. 49% received treatment for upper airway cough syndrome (UACS) with minimal benefit. Yield of studies testing for UACS causes of cough were <10%. 55% of patients underwent PFT with methacholine challenge, with 15% diagnostic of asthma. 40% received a 14 day course of oral corticosteroids (OCS), with half noting complete response of cough. 70% received a course of proton pump inhibitor, with 25% noting improvement in cough. 20% underwent formal reflux evaluation, with 2% patients demonstrating occult reflux by DeMeester criteria. Other investigations for cause of cough were yield <25%. 46% completed a trial of benzonatate, with 57% noting improvement in cough. 32% underwent cough suppression therapy (CST) with three fourths of patients achieving improvement in cough. 24% underwent a trial of TCA therapy, with those who tolerated TCA therapy achieving 72% improvement in cough. Conclusions: Many patients were referred still actively smoking or on ACE-inhibitor therapy. Trial of OCS was an effective diagnostic test to differentiate steroid-responsive and steroid-unresponsive cough. Many patients who responded to OCS had normal pulmonary function tests. Upper airway cough syndrome and reflux disease were less prevalent than described in the literature. Tricyclic antidepressants, gabapentin, and pregabalin were useful for treating cough not otherwise attributable to UACS, asthma, or reflux. Benzonatate and cough suppression therapy were effective adjuvant treatments. Key Words: Chronic cough, evaluation, treatment, upper airway cough syndrome, asthma, eosinophilic bronchitis, laryngopharyngeal reflux, corticosteroids, amitryptiline, postviral vagal neuropathy, cough suppression therapy Level of Evidence: 2b.
The Laryngoscope 01/2011; 121(S5). DOI:10.1002/lary.22207 · 2.14 Impact Factor
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ABSTRACT: To evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) in the diagnosis of chronic cough.
A total of 106 subjects with chronic cough and normal chest radiographs were recruited from October 2009 to September 2010. Based on the management guidelines of the Chinese Respiratory Society for cough, the golden standard methods were used to make the definite diagnosis of chronic cough, including sputum cell counts, pulmonary function tests, bronchial hyperresponsiveness, 24-h esophageal pH monitoring, skin pricking test and serum immunoglobulin E. All subjects received a FeNO test by a NIOXMINO analyzer. The values of FeNO to diagnose cough variant asthma (CVA) from chronic cough and EB from non-asthma cough were respectively assessed by the receiver operating characteristic (ROC) curves.
Among them, the definite diagnoses were cough variant asthma (CVA, n = 39), eosinophilic bronchitis (EB, n = 30) and other causes (n = 37). The FeNO levels in CVA [(54 ± 21) ppb)] (1 ppb = 1 × 10(9) mol/L) were significantly higher than those in EB [(34 ± 17) ppb, P < 0.01] and other causes [(21 ± 10) ppb, P < 0.01]. And the FeNO levels in EB were higher than those in other causes (P < 0.01). To diagnose CVA from chronic cough, the optimal FeNO cutoff value was 40 ppb with a sensitivity of 75%, a specificity of 86%, a positive predictive value of 77%, a negative predictive value of 86% and an accuracy of 81%. To diagnose EB from non-asthma chronic cough, the optimal FeNO cutoff value was 31 ppb with a sensitivity of 63%, a specificity of 92%, a positive predictive value of 88%, a negative predictive value of 92% and an accuracy of 72% respectively.
There are significant differences between the FeNO levels of different causes of chronic cough. A marked elevation of FeNO level helps to make a final diagnosis of CVA or EB. FeNO test is useful for making the diagnosis and differential diagnosis of chronic cough in clinic practices.
Zhonghua yi xue za zhi 05/2011; 91(18):1254-8. DOI:10.3760/cma.j.issn.0376-2491.2011.18.008
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