What is the first step to evaluate Chronic Obstructive Pulmonary Disease (COPD)?

First Step to Evaluate COPD

Spirometry is the required first step to evaluate and establish a diagnosis of COPD, with a post-bronchodilator FEV1/FVC ratio less than 0.70 confirming the presence of persistent airflow limitation. 1

When to Consider COPD and Perform Spirometry

Spirometry should be performed in individuals who present with:

• Respiratory symptoms:

  • Progressive dyspnea (especially with exercise)
  • Chronic cough (may be intermittent or unproductive)
  • Regular sputum production
  • Recurrent wheezing or chest tightness
  • Recurrent lower respiratory tract infections

• Risk factors:

  • Age over 40 years
  • History of tobacco smoking
  • Occupational exposures to dusts, vapors, fumes, gases
  • Biomass fuel exposure
  • Family history of COPD

Spirometry Testing Procedure

The proper spirometry procedure includes:

1. Post-bronchodilator measurement (performed after administration of an adequate dose of at least one short-acting bronchodilator)
2. Measurement of FEV1 (forced expiratory volume in 1 second)
3. Measurement of FVC (forced vital capacity)
4. Calculation of FEV1/FVC ratio

A post-bronchodilator FEV1/FVC ratio less than 0.70 confirms the presence of persistent airflow limitation and establishes the diagnosis of COPD 1.

Classification of Severity

Once COPD is confirmed by spirometry, severity can be classified based on FEV1 percent predicted:

Severity	Post-bronchodilator FEV1/FVC	FEV1 % Predicted
Mild	<0.70	≥80%
Moderate	<0.70	50-79%
Severe	<0.70	30-49%
Very severe	<0.70	<30%

Important Considerations

• Quality control: Good-quality spirometry requires a trained operator using a spirometer that provides quality feedback to ensure acceptable and repeatable results 2.

• Diagnostic stability: Up to one-third of patients initially diagnosed with COPD may shift to non-obstructed category when retested after 1-2 years, suggesting that diagnosis should not be based on a single spirometry test 3.

• Fixed ratio vs. Lower Limit of Normal (LLN): While the fixed ratio of FEV1/FVC <0.70 is commonly used, it may result in more frequent diagnosis in the elderly and less frequent diagnosis in adults younger than 45 years compared to using the LLN 1. The GOLD guidelines favor the fixed ratio for its diagnostic simplicity and consistency 1.

Common Pitfalls to Avoid

1. Relying solely on symptoms: The presence of symptoms is not a reliable indicator of disease, and diagnosis is often delayed until more severe airflow obstruction is present 2.

2. Prescribing inhalers without confirmation: Inhalers for COPD are expensive and carry risk of side effects, so they should not be prescribed without confirming airway obstruction through spirometry 4.

3. Inadequate spirometry technique: Poor technique can lead to misdiagnosis. If good quality spirometry is not available in primary care, patients should be referred to a specialized facility 4.

4. Single test diagnosis: Given the implications of a COPD diagnosis, it should not be based on a single spirometry test, as diagnostic category can shift over time 3.

After confirming COPD with spirometry, a comprehensive assessment should include evaluation of:

1. Symptom burden (using tools like mMRC or CAT)
2. Exacerbation history
3. Comorbidities
4. Impact on quality of life

This complete assessment will guide appropriate treatment decisions and improve patient outcomes.