What are the testing procedures and screening results for chronic obstructive pulmonary disease (COPD)?

COPD Testing Procedures and Screening Results

Spirometry is the required test for diagnosing COPD, which measures airflow obstruction through post-bronchodilator FEV1/FVC ratio <0.70 and confirms the severity based on FEV1 percentage of predicted value. 1, 2

Diagnostic Algorithm for COPD

Step 1: Clinical Assessment

• Consider COPD in individuals over 40 years with progressive dyspnea that worsens with exercise and persists over time 1
• Evaluate for chronic cough (may be intermittent and unproductive) and chronic sputum production 1
• Document smoking history (>40 pack-years is the best predictor of airflow obstruction) and occupational/environmental exposures 2, 1
• Record family history of COPD or other respiratory diseases 1
• Assess exercise tolerance to monitor future changes in breathlessness 1

Step 2: Physical Examination

• Physical examination alone is rarely diagnostic in COPD 1
• The combination of patient-reported smoking history >55 pack-years, wheezing on auscultation, and patient self-reported wheezing strongly suggests airflow obstruction (LR, 156) 2
• Signs of airflow limitation/hyperinflation usually only appear with significantly impaired lung function 1
• A normal physical examination is common in early COPD 2

Step 3: Spirometry (Required for Diagnosis)

• Post-bronchodilator spirometry is essential to confirm airflow obstruction 1, 2
• COPD is diagnosed when spirometry demonstrates airflow obstruction that is not fully reversible 2
• Diagnostic criteria: FEV1/FVC ratio <0.70 post-bronchodilator 2, 1
• Severity classification based on FEV1 percentage of predicted value 2:
  • Mild COPD: FEV1/FVC <0.7 and FEV1 >80% predicted
  • Moderate COPD: FEV1/FVC <0.7 and FEV1 50-80% predicted
  • Severe COPD: FEV1/FVC <0.7 and FEV1 30-50% predicted
  • Very severe COPD: FEV1/FVC <0.7 and FEV1 <30% predicted

Step 4: Additional Testing (As Indicated)

• Bronchodilator reversibility testing to differentiate COPD from asthma 1
  • A positive response is considered when FEV1 increases by 200 ml and 15% of baseline value 1
• Chest radiography if another diagnosis is being considered, but not needed for diagnosis of mild COPD 1
• CT scanning can help differentiate between structural abnormalities causing airflow limitation and identify comorbidities 1

Multidimensional Assessment for Treatment Selection

• The GOLD strategy recommends a multidimensional assessment for treatment selection 2:
  1. Symptom assessment using validated questionnaires (mMRC dyspnea scale, COPD Assessment Test, or clinical COPD questionnaire)
  2. Severity of airflow limitation based on spirometry
  3. Number of yearly exacerbations

Modified Medical Research Council (mMRC) Dyspnea Scale

• Grade 0: Not troubled with breathlessness except during strenuous exercise 2
• Grade 1: Troubled by shortness of breath when hurrying or walking up a slight hill 2
• Grade 2: Walks slower than people of the same age due to breathlessness or stops for breath when walking at own pace 2
• Grade 3: Stops for breath after walking about 100 meters or after a few minutes on level ground 2
• Grade 4: Too breathless to leave the house or breathless when dressing/undressing 2

Common Pitfalls in COPD Diagnosis

• Relying solely on history and physical examination without spirometry leads to inaccurate diagnosis 3, 4
• Only about one-third of patients with a diagnosis of COPD have spirometry to confirm their diagnosis 3
• Misclassification in elderly patients may occur due to the fixed FEV1/FVC ratio, resulting in more frequent diagnosis of COPD 1
• The absence of smoking history and no evidence of wheezing on either history or physical examination is the best combination to rule out airflow obstruction 2

Indications for Specialist Referral

• Suspected severe COPD 2
• Onset of cor pulmonale 2
• Assessment for oxygen therapy 2
• Bullous lung disease 2
• COPD in patient less than 40 years (to identify α-antitrypsin deficiency) 2
• Uncertain diagnosis 2
• Symptoms disproportionate to lung function deficit 2
• Frequent infections (to exclude bronchiectasis) 2

Importance of Early Detection

• COPD often has its roots decades before the onset of symptoms 2
• Impaired growth of lung function during childhood and adolescence may lead to lower maximally attained lung function in early adulthood 2
• Early intervention can potentially slow disease progression and improve outcomes 5