What is the next best step in managing an elderly patient with a chronic cough unresponsive to doxycycline and steroids?

Management of Chronic Cough Unresponsive to Doxycycline and Steroids in an Elderly Patient

The next best step is to obtain a chest CT scan to evaluate for underlying structural pathology, malignancy, or interstitial lung disease, followed by systematic evaluation and treatment for the most common causes: upper airway cough syndrome (UACS), asthma/non-asthmatic eosinophilic bronchitis (NAEB), and gastroesophageal reflux disease (GERD). 1

Critical Initial Considerations

Imaging and Diagnostic Workup

• Chest radiograph and spirometry are mandatory in all patients with chronic cough (>8 weeks duration). 1
• If the chest X-ray shows abnormalities suggestive of malignancy, interstitial disease, or infection, chest CT followed by bronchoscopy or transthoracic fine-needle aspiration should be the immediate next step. 1 This is particularly important in elderly patients where malignancy risk is elevated.
• High-resolution CT (HRCT) may be valuable when other targeted investigations are normal, especially to evaluate for interstitial lung disease or bronchiectasis. 1

Medication Review

• If the patient is on an ACE inhibitor, it must be stopped immediately regardless of temporal relationship to cough onset, as ACE inhibitor-induced cough can persist and the original cause may have resolved. 1 Cough typically resolves within days to 2 weeks (median 26 days) after discontinuation. 1

Systematic Algorithmic Approach

Step 1: Evaluate and Treat Upper Airway Cough Syndrome (UACS)

• Begin with a first-generation antihistamine-decongestant (A/D) combination as initial empiric therapy, as UACS is the most common cause of chronic cough. 1
• Response typically occurs within days to 1-2 weeks, though complete resolution may take several weeks to months. 1
• If partial response occurs with persistent nasal symptoms, add topical nasal corticosteroid, nasal anticholinergic, or nasal antihistamine. 1
• If symptoms persist, obtain sinus imaging (CT or plain films) to evaluate for acute or chronic sinusitis. 1
• Treat documented sinusitis with antibiotics and short-term nasal vasoconstrictor therapy. 1

Step 2: Evaluate and Treat Asthma or NAEB

Since the patient already received steroids without improvement, this requires careful reconsideration:

• Bronchial provocation testing (methacholine challenge) should be performed if spirometry is normal to definitively evaluate for asthma. 1, 2
• A negative bronchial provocation test excludes asthma but does not rule out steroid-responsive cough. 1
• Induced sputum for eosinophil count should be obtained to distinguish NAEB from other causes. 1, 2
• Fractional exhaled nitric oxide (FENO) can assess eosinophilic inflammation and predict corticosteroid responsiveness. 2

Treatment approach if asthma/NAEB is confirmed:

• Inhaled corticosteroids (ICS) are first-line treatment (equivalent to beclomethasone 200-800 μg daily), not systemic steroids. 1, 2 The previous oral steroid trial may have been inadequate in dose, duration, or delivery method.
• If response is incomplete after 4-8 weeks, increase ICS dose up to 2000 μg beclomethasone equivalent daily. 1, 2
• Add a leukotriene receptor antagonist (montelukast) if ICS alone is insufficient. 1, 2
• Consider adding long-acting beta-agonists in combination with ICS. 1

Important caveat: If there was no response to a 2-week oral steroid trial, cough is unlikely due to eosinophilic airway inflammation. 1 However, the lack of response to previous steroids in this case may reflect inadequate treatment of other coexisting causes rather than absence of asthma/NAEB. 1

Step 3: Evaluate and Treat GERD

• GERD is a commonly missed cause of treatment failure and can occur without gastrointestinal symptoms. 1
• Intensive acid suppression with proton pump inhibitors (PPIs) and alginates should be undertaken for a minimum of 3 months. 1
• Empirical treatment should be offered before oesophageal testing, as no current test of esophageal function reliably predicts treatment response. 1
• GERD commonly coexists with asthma and UACS, and cough will not resolve until all contributing factors are treated. 1, 2

Critical Understanding: Multifactorial Nature

Chronic cough is frequently multifactorial—patients commonly have two or all three of UACS, asthma, and GERD simultaneously. 1 The cough will not resolve until all contributing causes are effectively treated. 1 Therapy should be given in sequential and additive steps rather than stopping one treatment when starting another. 1

When to Refer

Referral to a specialist cough clinic is indicated when:

• Cough remains undiagnosed after systematic evaluation of UACS, asthma/NAEB, and GERD. 1
• There is no response to appropriate empiric trials of treatment. 1
• Chest imaging reveals concerning findings requiring subspecialty evaluation. 1

Common Pitfalls to Avoid

• Failing to recognize that the previous doxycycline trial was likely inappropriate unless there was documented bacterial sinusitis or COPD exacerbation. 1, 3 Antibiotics have no role in most chronic cough cases.
• Assuming oral steroids adequately treated asthma/NAEB—inhaled corticosteroids with proper technique are required for sustained benefit. 1, 2, 4
• Not treating GERD empirically even in the absence of reflux symptoms, as this is a frequent cause of treatment failure. 1
• Stopping one treatment when starting another rather than using additive sequential therapy. 1
• Not considering malignancy or tuberculosis in elderly patients, especially those from endemic areas or with systemic symptoms. 1