Evaluation of chronic cough - Differentials | BMJ Best Practice US
Evaluation of chronic cough - Differentials | BMJ Best Practice US
frequent throat clearing, postnasal drip, nasal discharge, nasal obstruction or sneezing typical, halitosis
mucopurulent secretions in the nasopharynx and oropharynx or cobblestone appearance of posterior oropharynx
response to empiric therapy with antihistamine and decongestant
There is no definitive test that can prove or disprove the presence of UACS; a combination of symptoms, physical examination findings, and response to therapy is required for diagnosis.[44]Pratter MR. Chronic upper airway cough syndrome secondary to rhinosinus diseases (previously referred to as postnasal drip syndrome): ACCP evidence-based clinical practice guidelines. Chest. 2006 Jan;129(1 suppl):63S-71.http://journal.chestnet.org/article/S0012-3692(15)52833-X/fulltexthttp://www.ncbi.nlm.nih.gov/pubmed/16428694?tool=bestpractice.comWhen a specific cause for UACS (e.g., allergic rhinitis or nasal polyposis) is suspected based on history and physical exam, therapy should first be directed toward those entities.
wheezing, chest tightness, dyspnea, symptom variability, strong family history of asthma/atopic disease, cough, paroxysms, exacerbation by irritants or seasonal exposures; cough may sometimes be the principal or sole symptom, usually worse at night (cough-variant asthma)
wheezing and prolonged expiratory phase on pulmonary exam
FEV1/forced vital capacity (FVC) ratio: below the lower limit of normal (LLN; if available) or <70% (if LLN not available) is positive for airflow obstruction; BDR test: improvement in FEV1 of 12% or more in response to beta agonists (or to a treatment trial with corticosteroids), together with an increase in volume of 200 mL or more is positive for reversibility of airway obstruction
FEV1/FVC ratio (spirometry) is the primary diagnostic test.[11]Global Initiative for Asthma. Global strategy for asthma management and prevention (2025 update). May 2025 [internet publication].https://ginasthma.org
A bronchodilator reversibility test may demonstrate reversibility of airflow obstruction in response to short-acting bronchodilators.[11]Global Initiative for Asthma. Global strategy for asthma management and prevention (2025 update). May 2025 [internet publication].https://ginasthma.org[31]Louis R, Satia I, Ojanguren I, et al. European Respiratory Society guidelines for the diagnosis of asthma in adults. Eur Respir J. 2022 Feb 15:2101585.https://www.doi.org/10.1183/13993003.01585-2021http://www.ncbi.nlm.nih.gov/pubmed/35169025?tool=bestpractice.com[59]National Institute for Health and Care Exellence. Asthma: diagnosis, monitoring and chronic asthma management (BTS, NICE, SIGN). Nov 2024 [internet publication].https://www.nice.org.uk/guidance/ng245
Spirometry can be normal in some patients.[31]Louis R, Satia I, Ojanguren I, et al. European Respiratory Society guidelines for the diagnosis of asthma in adults. Eur Respir J. 2022 Feb 15:2101585.https://www.doi.org/10.1183/13993003.01585-2021http://www.ncbi.nlm.nih.gov/pubmed/35169025?tool=bestpractice.comIf normal, further investigations such as bronchoprovocation testing are recommended.[Figure caption and citation for the preceding image starts]:Flow-volume loop (spirogram) in obstructive lung disease, such as asthma or COPD: peak expiratory flow may be normal, but a concave shape is seen following the point of maximal flow due to the low flow rate in relation to lung volumeCreated by BMJ Knowledge Centre[Citation ends].
may be reduced; may be variability (>10%) of measurements recorded at different times of the day
PEF should be measured in patients with normal spirometry. Variability of airway obstruction can be used to support the diagnosis of asthma.[31]Louis R, Satia I, Ojanguren I, et al. European Respiratory Society guidelines for the diagnosis of asthma in adults. Eur Respir J. 2022 Feb 15:2101585.https://www.doi.org/10.1183/13993003.01585-2021http://www.ncbi.nlm.nih.gov/pubmed/35169025?tool=bestpractice.com[60]National Asthma Education and Prevention Program. Expert panel report 3: guidelines for the diagnosis and management of asthma: full report 2007. Aug 2007 [internet publication].https://www.nhlbi.nih.gov/health-topics/guidelines-for-diagnosis-management-of-asthma[61]Expert Panel Working Group of the National Heart, Lung, and Blood Institute (NHLBI) administered and coordinated National Asthma Education and Prevention Program Coordinating Committee (NAEPPCC)., Cloutier MM, Baptist AP, et al. 2020 Focused updates to the asthma management guidelines: a report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group. J Allergy Clin Immunol. 2020 Dec;146(6):1217-70.https://www.jacionline.org/article/S0091-6749(20)31404-4/fulltexthttp://www.ncbi.nlm.nih.gov/pubmed/33280709?tool=bestpractice.comThe diagnosis of asthma is supported if there is excessive variability in twice daily PEF over 2 weeks. In adults, an average daily diurnal variability in PEF of >10% is considered excessive. An increase in PEF by >20% from baseline after 4 weeks of treatment also indicates excessive variability.[11]Global Initiative for Asthma. Global strategy for asthma management and prevention (2025 update). May 2025 [internet publication].https://ginasthma.org
In an untreated patient, absence of elevated FeNO would make asthma unlikely.[62]Chatkin JM, Ansarin K, Silkoff PE, et al. Exhaled nitric oxide as a noninvasive assessment of chronic cough. Am J Respir Crit Care Med. 1999 Jun;159(6):1810-3.http://www.atsjournals.org/doi/full/10.1164/ajrccm.159.6.9809047http://www.ncbi.nlm.nih.gov/pubmed/10351923?tool=bestpractice.com
improvement in symptoms following a 2-4 week course of an inhaled corticosteroid or a leukotriene receptor antagonist
provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) <4 mg/mL
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