What guideline recommends Pulmonary Function Testing (PFT) for adolescents with asthma?

Guidelines for Pulmonary Function Testing in Adolescents with Asthma

The 2021 European Respiratory Society (ERS) clinical practice guidelines strongly recommend pulmonary function testing as a first-line diagnostic test for adolescents with asthma aged 5-16 years, requiring at least two objective test results to confirm diagnosis. 1

Key Diagnostic Tests Recommended

First-Line Tests

• Spirometry with bronchodilator reversibility (BDR) testing

  • Abnormal results defined as FEV1 or FEV1/FVC less than lower limit of normal and/or <80% predicted
  • BDR positive if ≥12% and/or ≥200 mL improvement after bronchodilator 1

• Fractional exhaled nitric oxide (FeNO) measurement

  • Recommended cut-off of ≥25 ppb
  • Should ideally be performed before spirometry 2

Additional Tests (When First-Line Tests Are Inconclusive)

• Peak Expiratory Flow Rate (PEFR) Variability

  • Measured over 2 weeks with twice-daily measurements
  • Variability ≥12% considered significant 1

• Challenge Testing

  • Recommended when other tests fail to confirm diagnosis
  • Options include direct bronchial challenge with methacholine or indirect testing using exercise 1

Diagnostic Algorithm for Adolescents with Asthma

1. Perform spirometry first

   • If abnormal → Perform bronchodilator reversibility testing
     • If BDR positive (≥12% and/or ≥200 mL) → Asthma confirmed
     • If BDR negative → Perform FeNO measurement

2. If spirometry normal

   • Perform FeNO measurement
     • If FeNO ≥25 ppb → Asthma confirmed
     • If FeNO <25 ppb → Consider PEFR variability testing or challenge testing 1

Clinical Importance of PFT in Adolescents

• PFTs provide objective assessment of asthma severity beyond symptom reporting
• Studies show approximately one-third of children with symptoms of mild intermittent or mild persistent asthma would be reclassified into higher severity categories when pulmonary function is considered 3
• This reclassification has direct implications for preventing undertreatment of asthma

Implementation Challenges

• PFT is underutilized by physicians, particularly among primary care providers
• Only 34% of primary care physicians report measuring pulmonary function in at least 75% of their asthma patients, compared to 83% of asthma specialists 4
• Key barriers include:
  • Lack of access to spirometry equipment
  • Insufficient training in performing and interpreting tests
  • Perception that testing requires excessive office resources 4

Monitoring Recommendations

• The 2024 Global Initiative for Asthma (GINA) report emphasizes that objective lung function measurements are necessary for confirming asthma diagnosis and continued monitoring 1
• Regular monitoring of lung function is recommended to:
  • Assess response to treatment
  • Detect early deterioration
  • Identify potential exacerbation triggers

Pitfalls to Avoid

• Relying solely on symptoms: Over-reliance on symptoms alone for diagnosis should be avoided 2
• Skipping PFT in mild cases: Even patients with mild symptoms may have significant airflow limitation
• Misinterpreting results: FEF25-75 may be a better spirometric parameter for predicting mild asthma, while FEV1 is better for assessing overall severity 5
• Using treatment response alone: A "trial of preventer medication" is not sufficient as a diagnostic test without objective improvement in lung function 1

By implementing these guideline recommendations for pulmonary function testing in adolescents with asthma, clinicians can improve diagnostic accuracy, appropriately classify disease severity, and optimize treatment decisions to reduce morbidity and mortality.