In a patient with a post‑bronchodilator FEV1/FVC ratio below 70%, documented bronchodilator reversibility, long‑term cigarette smoking, wheezing and dyspnea, does this indicate asthma‑COPD overlap?

Asthma-COPD Overlap: Diagnostic Considerations

The clinical presentation described—post-bronchodilator FEV1/FVC <70%, bronchodilator reversibility, prolonged smoking history, wheezing, and dyspnea—is suggestive but not definitively diagnostic of asthma-COPD overlap, and importantly, bronchodilator response alone should not be relied upon to make this distinction.

Critical Limitation of Bronchodilator Response

The presence of bronchodilator reversibility in a patient with COPD does not reliably indicate asthma-COPD overlap:

• Bronchodilator response (BDR) is not reproducible, not related to other typical asthma features, does not predict inhaled corticosteroid responsiveness, and is not specific for asthma-COPD overlap 1
• BDR represents "phenotype mimicry"—while it is an accepted feature of asthma, it does not usefully recognize asthma in the setting of COPD 1
• BDR is at least as common in COPD patients as in asthma patients, with prevalence of 18.4% versus 17.3% respectively, making it of limited value for distinguishing between these conditions 2

What Additional Features Would Support Asthma-COPD Overlap?

To more confidently identify asthma-COPD overlap, look for additional major criteria beyond just BDR:

Czech Guideline Major Criteria 1:

• Strong bronchodilator positivity (FEV1 >15% AND >400 mL)—note this is more stringent than standard BDR
• Positive bronchoconstrictor test (methacholine challenge)
• Elevated FeNO ≥45-50 ppb and/or sputum eosinophils ≥3%
• History of asthma

Supporting Minor Criteria 1:

• Mild BDR positivity (FEV1 >12% and >200 mL)
• Elevated total IgE
• History of atopy

Diagnosis requires either two major criteria OR one major plus two minor criteria 1

Clinical Characteristics That Distinguish Overlap

Patients with true asthma-COPD overlap demonstrate:

• Lower diffusing capacity (DLCO/VA 86% predicted versus 98% in non-overlap) 3
• Higher blood neutrophil levels (4.50 versus 3.60×10⁹ L⁻¹) 3
• Elevated IL-6 levels (2.88 versus 1.52 pg·mL⁻¹) 3
• Greater remaining bronchial reversibility beyond standard BDR thresholds 3
• More comorbidities 3

Current Guideline Perspective

The concept of asthma-COPD overlap as a distinct diagnostic entity has been challenged and some experts recommend abandoning it as a specific phenotype 1. Instead, a multidimensional assessment approach is preferred that identifies and treats individual pathological processes rather than forcing patients into a single diagnostic category 1.

Practical Approach for This Patient

For your patient with post-bronchodilator obstruction, BDR, smoking history, and symptoms:

1. Obtain additional testing to look for asthma features:

   • FeNO measurement
   • Sputum or blood eosinophil count
   • Total IgE if history suggests atopy
   • Detailed history of childhood respiratory symptoms or diagnosed asthma 1

2. Assess for stronger BDR (>15% and >400 mL improvement) rather than standard criteria 1

3. Consider methacholine challenge if clinically appropriate 1

4. If overlap features are confirmed, treatment should primarily follow asthma guidelines with inhaled corticosteroids plus long-acting bronchodilators, with COPD-specific approaches added as needed 4

Common Pitfall

Do not diagnose asthma-COPD overlap based solely on the presence of standard bronchodilator reversibility (≥12% and ≥200 mL) in a patient with fixed obstruction—this finding occurs commonly in COPD without asthma features and does not predict treatment response or clinical outcomes 1, 2.