Assessment of chronic cough

Common

Upper airway cough syndrome (postnasal drip)

History	Exam	1st test	Other tests
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	therapeutic trial: response to empirical therapyMore therapeutic trial 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. [17] When a specific cause for UACS, such as allergic rhinitis or nasal polyposis, is suspected based on history and physical examination, therapy should first be directed towards those entities.

Asthma

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History	Exam	1st test	Other tests
wheezing, chest tightness, dyspnoea, symptom variability, strong FHx of asthma/atopic disease, cough, paroxysms, exacerbation by irritants or seasonal exposures; cough may sometimes be the sole symptom (cough-variant asthma) [8]	wheezing and prolonged expiratory phase on pulmonary examination	spirometry with bronchodilator: reversible obstructive ventilatory defect; increase in FEV1 with bronchodilator 12% or more from baseline or 10% or more of predicted FEV1; FEV1/FVC <80% [19] More spirometry with bronchodilator Spirometry can be normal in some patients. If normal, bronchoprovocation testing is recommended.	morning vs midday peak expiratory flow (PEF) recording: variability >20%More morning vs midday peak expiratory flow (PEF) recording PEF should be measured in patients with normal spirometry. Variability of airway obstruction can be used to support the diagnosis of asthma. [19] exhaled nitric oxide (ENO): elevatedMore exhaled nitric oxide (ENO) Elevated ENO is not specific enough to diagnose asthma without further testing; however, in an untreated patient, absence of elevated ENO would make asthma unlikely. [24] bronchoprovocation testing: provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) <4 mg/mLMore bronchoprovocation testing Increased airway responsiveness is a sensitive but not specific feature of asthma. Negative methacholine challenge while not receiving inhaled corticosteroids essentially excludes asthma. [25]

Gastro-oesophageal reflux disease (GORD)

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History	Exam	1st test	Other tests
heartburn, dysphagia, acid regurgitation, association of cough with slouched posture, phonation, rising from bed, or eating suggest reflux disease; may be silent [18]	no differentiating features on examination	therapeutic trial of double-strength proton-pump inhibitors (PPIs) for 8 weeks: alleviation of symptoms may require 8 weeks of double-strength PPI therapy, so the trial should not be considered 'negative' before 8 weeks More therapeutic trial of double-strength proton-pump inhibitors (PPIs) for 8 weeks As reflux disease is clinically silent in 75% of cases, empirical therapy with a PPI should precede formal testing. [18] [26] Other medications included in the therapeutic trials are H2 blockers, prokinetics, and baclofen. [7]	24-hour oesophageal pH monitoring: pH <4 for 4% or more of monitoring time and coinciding with cough is consistent with pathological acid exposure More 24-hour oesophageal pH monitoring Most sensitive and specific for reflux disease-related cough. Testing first may be considered as an alternative to a PPI trial. Controversy exists in this regard. [26] Testing should be performed if a PPI trial does not resolve symptoms but GORD is still considered likely. A detailed assessment of symptom correlation with reflux events is most supportive of the diagnosis. [26] barium oesophagram: refluxMore barium oesophagram Not sensitive.

Non-asthmatic eosinophilic bronchitis (NAEB)

History	Exam	1st test	Other tests
chronic non-productive cough; no differentiating features on hx	no differentiating features on examination	sputum or broncho-alveolar lavage (BAL) differential count: eosinophiliaMore sputum or broncho-alveolar lavage (BAL) differential count Eosinophilia in sputum or BAL without obstruction on spirometry, without peak flow variability or hyperreactivity on bronchoprovocation testing, suggests NAEB. [27]	exhaled nitric oxide (ENO): elevatedMore exhaled nitric oxide (ENO) Sensitive in patients not treated with inhaled corticosteroids. [28] therapeutic response to inhaled steroids: presentMore therapeutic response to inhaled steroids Cough due to NAEB improves after a course of inhaled steroids for 4-6 weeks.

Chronic bronchitis

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History	Exam	1st test	Other tests
hx of smoking may be present; cough may produce sputum; dyspnoea, especially exertional, may accompany the cough	mild cases: most respiratory examinations are normal, may show quiet breath sounds, prolonged expiratory phase, rhonchi, or wheezes; advanced cases: cyanosis, barrel chest, use of accessory muscles of inspiration, increased S2 over left sternal border, or peripheral oedema	PFT: decreased FEV1, FEV1/FVC <70%, residual volume >120%, total lung capacity >120%, diffusion capacity for CO <80%More PFT Spirometric, lung volume, and diffusion capacity may be present in different combinations depending on the clinical presentation.	CXR: hyperinflation, but may not be present in some cases

Angiotensin-converting enzyme inhibitor (ACE inhibitor)

History	Exam	1st test	Other tests
dry cough, typically associated with tickling or scratching sensation in the throat; cough may begin within days or months of onset of ACE inhibitor therapy	no specific examination findings	stop ACE inhibitor use: resolution of coughMore stop ACE inhibitor use Stopping ACE inhibitor resolves cough in 1-12 weeks, typically 1-4 weeks. [29]

Pneumonia

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History	Exam	1st test	Other tests
fever, malaise, cough, usually productive of sputum, chest pain	dullness to percussion, decreased breath sounds, and presence of rales	CXR: infiltrate suggestive of pneumonia	WCC (blood): usually elevated but non-specific sputum Gram stain and culture: presence of micro-organisms and leukocytes in a good sputum sample (<25 squamous epithelial cells per field) supports the diagnosis of respiratory tract infection

Post-infectious cough

History	Exam	1st test	Other tests
cough of duration between 3 and 8 weeks following symptoms of acute respiratory infection; nasal/sinus congestion, non-purulent nasal discharge, sore throat [31]	normal CXR; diagnosis is clinical and one of exclusion	CXR: normal, rules out pneumonia	WCC (blood): usually elevated but non-specific sputum Gram stain and culture: presence of micro-organisms and leukocytes in a good sputum sample (<25 squamous epithelial cells per field) supports the diagnosis of respiratory tract infection

Bordetella pertussis infection

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History	Exam	1st test	Other tests
paroxysms of cough, post-tussive vomiting, or inspiratory whooping sound; more likely if local epidemiology suggests increased prevalence	petechiae and conjunctival haemorrhages may result from cough paroxysms; lung examination is typically normal	nasopharyngeal culture (if symptoms <2 weeks): positiveMore nasopharyngeal culture (if symptoms <2 weeks) In presence of symptoms, pertussis should be diagnosed using appropriate tests when available, unless another diagnosis is proven. [31] Patient should be isolated for 5 days and case reported to public health authorities. Enriched media is required for culturing.	rapid PCR, and/or serology (if symptoms present >4 weeks): positive

Uncommon

Lung cancer

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History	Exam	1st test	Other tests
hx of tobacco smoking, change in character of chronic cough, haemoptysis, hoarseness, chest pain, weight loss, superior vena cava syndrome (localised oedema of face and upper extremities, facial plethora, distended neck and chest veins), symptoms related to distant metastases and advanced stages of cancer	central lung cancers may cause unilateral localised wheezing; superior vena cava syndrome; cachexia and symptoms related to distant metastases (e.g., bone pain) are late symptoms	CXR: presence of the lesionMore CXR Up to 26% of the parenchyma may not be adequately visualised on a CXR. [30]	CT chest: presence of the lesion and loco-regional disease sputum cytology: may document presence of malignant cells bronchoscopy: presence of tumourMore bronchoscopy Allows visualisation of extent of tumour and collection of material for biopsy.

Bronchiectasis and chronic suppurative lung disease

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History	Exam	1st test	Other tests
cough productive of large amounts of mucopurulent sputum, diurnal variation (e.g., worse in the morning), positional worsening; dyspnoea, wheezing, haemoptysis; paroxysmal cough non-productive of sputum may sometimes be present	crackles and wheezing, predominantly over lower lobes; clubbing in a minority of patients	CXR: increased bronchovascular markingsMore CXR Sensitive but not specific finding. Should be the first examination if high-resolution CT not available. high-resolution CT chest: dilations of the bronchi, size of the bronchi exceeding the size of the accompanying artery More high-resolution CT chest Should be the first examination if available.	PFT: irreversible obstructive defect, with FEV1/FVC <70%

Interstitial pulmonary fibrosis

History	Exam	1st test	Other tests
dyspnoea of sub-acute onset dominates the clinical picture; cough typically dry	dry, velcro crackles, typically over lung bases; clubbing may be present	CXR: increased interstitial markingsMore CXR First test if high-resolution CT not available. high-resolution CT chest: interstitial pneumonitis: patchy, predominantly basilar and sub-pleural reticular changes with honeycombing and traction bronchiectasis in later stages of the diseaseMore high-resolution CT chest Confirmatory, sensitive and specific. Findings depend on specific interstitial pathology. Interstitial pneumonitis is the most common form.	PFT: restrictive pattern with total lung capacity <80%, functional residual capacity <80%, and vital capacity <80%, with diffusion capacity for CO <80% biopsy: pattern of usual interstitial pneumonia

Sarcoidosis

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History	Exam	1st test	Other tests
most patients asymptomatic; symptomatic patients: shortness of breath, dyspnoea on exertion, and chest pain are present in minority of patients; low-grade fever; other symptoms reflect involvement of various organs	most often normal; skin lesions (erythema nodosum and maculopapular skin lesions), enlargement of lacrimal glands, lymphadenopathy in cervical, supraclavicular, or axillary areas; redness of eye, tearing, and photophobia may represent uveitis	CXR: various findings, bilateral hilar and mediastinal lymphadenopathy, reticular infiltrates; fibrosis with decreased lung volumes in late sarcoidosisMore CXR Severity of radiographic lung involvement may not correlate with severity of physiological deficit.	chest CT with high-resolution cuts: bilateral hilar and mediastinal lymphadenopathy, interstitial infiltrates PFTs (spirometry, lung volumes, diffusion capacity): often normal, but may show non-specific reduction in diffusion capacity, obstruction, restriction, or mixed picture More PFTs (spirometry, lung volumes, diffusion capacity) Not sensitive or specific for this disorder, but results may influence therapeutic choices once coupled with clinical and radiographic data bronchoscopy with biopsy: non-caseating granuloma is supportive, but other granulomatous disorders should be reasonably excluded with special stains and clinical assessmentMore bronchoscopy with biopsy When pulmonary involvement is present, has a high sensitivity.

Tuberculosis

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History	Exam	1st test	Other tests
residence in/visit to high-prevalence area, close contact with active TB; hx of anorexia, malaise, weight loss, fever, or night sweats; chronic cough productive of sputum, occasionally associated with haemoptysis; immunosuppressed status, especially AIDS	fever, cachexia, tachycardia; asymmetry in chest movement and dullness to percussion due to pleural effusion, bronchial breathing, crackles, rales due to an infiltrate or rhonchi in presence of significant bronchial purulence; palpable extra-thoracic lymphadenopathy is uncommon	CXR: primary TB: mid-lung infiltrate; secondary TB: predominantly upper lobe infiltrates with distinct tendency for fibrosis and volume lossMore CXR Calcified parenchymal and hilar lymph node granulomata may support the diagnosis; pleural effusion may accompany both primary and secondary TB.	sputum Gram stain and culture: presence of acid-fast bacilli (Ziehl-Neelsen stain) in sputum or broncho-alveolar lavage (BAL) More sputum Gram stain and culture Culture of Mycobacterium tuberculosis typically takes several weeks (up to 8); decisions on treatment are usually made before culture results are known. tuberculin skin test: positiveMore tuberculin skin test Reactivity to intra-dermal injection of tuberculin is primarily used to detect latent TB, but may be used as an adjunct in diagnosis of active TB. QuantiFERON: positiveMore QuantiFERON Detection of lymphocytes reacting to tuberculin in vitro is primarily used to detect latent TB, but may be used as an adjunct in diagnosis of active TB.

Foreign body

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History	Exam	1st test	Other tests
abrupt onset, more common in young children	may be asymptomatic or show signs of airways obstruction, including cough, wheeze, decreased breath sounds, dyspnoea, or fever	laryngoscopy/bronchoscopy: visualisation of foreign body CXR: visualisation of foreign body (if object is radio-opaque)	chest CT: visualisation of foreign body

Hypersensitivity pneumonitis

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History	Exam	1st test	Other tests
occupational/environmental exposure to allergens (e.g., farmers, bird breeders), progressive dyspnoea, fatigue, and weight loss	clubbing, increased respiratory rate, inspiratory crackles over lower lung fields	CXR: fibrotic changes; loss of lung volume particularly affecting the upper lobes	chest CT: features of fibrosis

Bronchiolitis

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History	Exam	1st test	Other tests
age <1 year, cough, wheeze, and dyspnoea, hx of prematurity, underlying cardiopulmonary disease or immunodeficiency	high respiratory rate, accessory muscle use, retractions, wheezes, crackles, purulent secretions on bronchoscopy	CXR: consolidation and atelectasis in severe disease	virology: may be positive for respiratory syncytial virusMore virology Rarely useful in making management decisions. high-resolution CT scan: signs of small airways disease

Recurrent aspiration

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History	Exam	1st test	Other tests
dysphagia, association of cough with eating/drinking, fear of choking with eating/drinking; may have hx of neurological disease including stroke, multiple sclerosis, Parkinson's disease	signs of neurological disease such as stroke, multiple sclerosis, Parkinson's disease	CXR: persistent lower lobe infiltrates swallow evaluation: aspiration More swallow evaluation Patient should be referred to speech-language pathologist for this evaluation. [3]

Tropical filarial pulmonary eosinophilia

History	Exam	1st test	Other tests
Travel to endemic area (sub-Saharan Africa, Indian subcontinent, southeast Asia, Oceania); dry, paroxysmal cough, frequently nocturnal	Frequently normal; wheezing, rhonchi, crackles may be present on lung exam; some patients develop hepatosplenomegaly	blood count with differential: eosinophilia CXR: increased interstitial markings	filarial antibody levels: elevated serum IgE: elevated

Psychogenic cough

History	Exam	1st test	Other tests
extensive evaluation has ruled out other causes	cough improves following behaviour modification or psychiatric therapy	none: extensive evaluation has already ruled out other causes