What is the best approach to diagnose and manage a patient with a chronic cough lasting over 25 years?

Chronic Cough Lasting Over 25 Years: Diagnostic and Management Approach

For a patient with chronic cough persisting over 25 years, begin with mandatory baseline investigations—chest radiograph and spirometry with bronchodilator response—then systematically pursue the three most common causes (upper airway cough syndrome, asthma, and gastroesophageal reflux disease) through sequential empiric treatment, as this algorithmic approach is more cost-effective than extensive upfront testing and successfully resolves cough in the majority of cases. 1, 2

Initial Mandatory Investigations

All patients require:

• Chest radiograph to exclude malignancy, infection, structural abnormalities, bronchiectasis, or interstitial lung disease 3, 1
• Spirometry with bronchodilator response to identify airflow obstruction and assess reversibility suggesting asthma 3, 1
• Assessment of cough severity and quality of life impact using validated visual analogue scores or cough-specific questionnaires 1

Critical History Elements to Identify

Medication review:

• Discontinue ACE inhibitors immediately if present—resolution typically occurs within days to 2 weeks (median 26 days), regardless of temporal relationship to cough onset 2

Smoking status:

• Current smoking is responsible for 85-90% of chronic bronchitis cases; cessation should be the priority intervention with most patients achieving resolution within 4 weeks 4, 2

Occupational exposures:

• Detailed assessment for dust, chemicals, fumes, or respiratory irritants 1, 4

Symptom patterns suggesting specific etiologies:

• UACS indicators: postnasal drip sensation, throat clearing, nasal discharge 4
• Asthma indicators: wheezing, chest tightness, dyspnea, nocturnal symptoms 4
• GERD indicators: heartburn, regurgitation, dysphagia (though reflux-associated cough may occur without gastrointestinal symptoms) 1, 4

Red flags requiring urgent investigation:

• Hemoptysis, unintentional weight loss, fever, systemic illness, history of cancer, tuberculosis, or AIDS 4, 2

Sequential Empiric Treatment Algorithm

Given the 25-year duration, this represents either refractory disease or inadequately treated common causes. The three most common causes—upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD)—account for the vast majority of chronic cough cases and frequently coexist, requiring treatment of all contributing factors before cough resolves. 3, 1

Step 1: Upper Airway Cough Syndrome (UACS)

• Initiate first-generation antihistamine-decongestant combination therapy 1
• Allow adequate trial duration of several weeks before declaring treatment failure 4, 2
• UACS is the most common cause, accounting for approximately 44% of cases 2

Step 2: Asthma/Eosinophilic Airway Disease

If UACS treatment fails and spirometry is normal:

• Perform bronchial provocation testing (methacholine challenge) to assess for bronchial hyperresponsiveness, as cough-variant asthma commonly presents with normal spirometry 1, 2
• A negative methacholine challenge essentially excludes asthma 1
• If methacholine testing is unavailable, offer a 2-week trial of oral corticosteroids (e.g., prednisolone 30-40 mg daily) to diagnose eosinophilic airway inflammation; lack of response effectively rules it out 3, 1
• If positive, initiate inhaled corticosteroids with or without bronchodilators, even without spirometric evidence of obstruction 2

Step 3: Gastroesophageal Reflux Disease (GERD)

• Initiate intensive acid suppression therapy for at least 3 months—this is the minimum adequate trial duration 1, 4, 2
• GERD is frequently overlooked in general respiratory clinics as an extrapulmonary cause 2
• Empiric treatment is preferred over diagnostic testing (24-hour pH monitoring) as the initial approach 1

Common Pitfalls to Avoid

Inadequate treatment duration:

• GERD requires ≥3 months of intensive acid suppression for proper evaluation 1, 4
• UACS requires several weeks of antihistamine-decongestant treatment 4

Overlooking multifactorial etiology:

• Patients commonly have two or even all three common diagnoses simultaneously; cough will not resolve until all contributing factors are effectively treated 1

Relying solely on spirometry:

• Cough-variant asthma may present with normal spirometry and insufficient reversibility to meet traditional asthma criteria 3, 1, 2

Premature extensive testing:

• Sequential empiric treatment is more cost-effective than comprehensive upfront investigation when UACS prevalence is approximately 44% 2

Advanced Evaluation After Failed Empiric Treatment

Only after sequential treatment of all three common causes with adequate duration:

• Proceed to high-resolution CT (HRCT) chest to evaluate for bronchiectasis (accounts for up to 8% of chronic cough cases), interstitial lung disease, or occult malignancy 2
• HRCT identifies abnormalities in up to 42% of patients with presumed normal chest radiographs and is diagnostic in 24% of patients who failed initial protocols 2
• Up to 34% of CT-proven bronchiectasis cases have normal chest radiographs 2

Consider bronchoscopy:

• To look for occult airway disease (endobronchial tumor, sarcoidosis, suppurative infection, eosinophilic or lymphocytic bronchitis) 3
• Particularly if structural abnormalities or endobronchial lesions are suspected 1

Refractory Chronic Cough Management

If cough persists despite treating all common causes:

• Referral to a specialist cough clinic is appropriate before labeling as unexplained/idiopathic cough 3, 1
• Consider neuromodulatory treatment: low-dose morphine (preferred), gabapentin, pregabalin, and/or speech therapy 5, 6
• Uncommon causes to consider: nonacid reflux disease, swallowing disorder, congestive heart failure, or habit cough based on clinical findings 3