What is the most appropriate workup for a 78-year-old male patient with a history of upper respiratory tract infection symptoms, including nasal congestion, persistent cough, fatigue, dyspnea, and insomnia, with exposure to secondhand smoke and a family history of lung cancer?

Comprehensive Workup for a 78-Year-Old Male with Respiratory Symptoms

The most appropriate workup for this 78-year-old male with persistent respiratory symptoms should include chest radiography, spirometry with bronchodilator testing, and evaluation for upper airway cough syndrome (UACS) as the initial steps, followed by additional targeted testing based on these results.

Initial Assessment and Rationale

Key Clinical Features Requiring Investigation

• Persistent symptoms for 3 months with worsening over past 3 weeks
• Nasal congestion, cough, fatigue, and dyspnea
• Symptoms exacerbated by physical activity
• History of secondhand smoke exposure
• Family history of lung cancer (late wife)
• Age (78 years) as a risk factor

First-Line Diagnostic Tests

1. Chest Radiography

   • Essential first step to rule out serious conditions, particularly pneumonia and lung cancer 1
   • Critical given the patient's family history of lung cancer and secondhand smoke exposure
   • Normal findings would direct workup toward common causes of chronic cough

2. Spirometry with Bronchodilator Testing

   • Necessary to evaluate for COPD and asthma 1
   • Should include pre- and post-bronchodilator FEV1/FVC to assess for fixed airflow limitation
   • A post-bronchodilator FEV1/FVC <0.70 would confirm persistent airflow limitation suggestive of COPD 1

3. Upper Airway Evaluation

   • Focused examination of nasal passages and throat
   • Consider empiric treatment for UACS with first-generation antihistamine-decongestant combination 1
   • Response to treatment would support UACS diagnosis

Secondary Testing Based on Initial Results

If Initial Tests Suggest COPD:

• Complete pulmonary function tests including lung volumes and diffusion capacity
• Assessment of oxygenation (pulse oximetry, arterial blood gas if indicated)
• COPD assessment test (CAT) or modified Medical Research Council (mMRC) dyspnea scale to evaluate symptom burden 1

If Initial Tests Suggest Upper Airway Involvement:

• Sinus imaging if symptoms persist after empiric treatment 1
• Consider nasal endoscopy to evaluate for structural abnormalities
• Allergy testing may be warranted given history of seasonal allergic rhinitis 1

If Initial Tests Are Inconclusive or Concerning:

• Chest CT scan if chest radiograph shows abnormalities or is normal but clinical suspicion remains high
• Consider bronchoscopy if there is concern for endobronchial lesions, especially given family history of lung cancer 1
• Evaluation for gastroesophageal reflux disease (GERD) as a potential contributor to chronic cough

Special Considerations

Multifactorial Etiology

• Chronic cough is often multifactorial, with UACS, asthma, and GERD being the three most common causes 1
• The patient may have multiple conditions requiring simultaneous treatment

Age-Related Factors

• In elderly patients, symptoms of COPD may be underreported or attributed to aging 1
• Careful assessment of dyspnea on exertion is particularly important

Comorbidity Assessment

• Evaluate for cardiovascular disease as a potential cause of dyspnea
• Consider sleep study if sleep disturbances suggest possible sleep-disordered breathing

Common Pitfalls to Avoid

1. Attributing symptoms solely to acute infection

   • The 3-month duration suggests chronic condition(s) rather than acute infection 1

2. Overlooking the significance of secondhand smoke exposure

   • Secondhand smoke is a risk factor for COPD and lung cancer 1

3. Failing to consider multiple concurrent diagnoses

   • Upper and lower airway diseases frequently coexist, especially in COPD patients 2

4. Delaying evaluation for potential malignancy

   • Family history of lung cancer with similar symptoms warrants thorough investigation 3

5. Treating empirically without objective testing

   • Spirometry is essential for diagnosis of obstructive lung disease and should not be skipped 1

By following this systematic approach, the clinician can efficiently identify the cause(s) of this patient's respiratory symptoms and initiate appropriate treatment to improve his quality of life and prevent further deterioration.