Asthma vs COPD
How to tell Asthma and COPD apart when a board question makes them look alike.
Asthma: obstruction reverses at least 12 percent and 200 mL after a bronchodilator; COPD: largely fixed obstruction.
Side by side
Episodic wheeze, cough, triggers, atopy, and reversible airflow obstruction.
Chronic progressive dyspnea in a smoker or exposure history with less reversible obstruction.
Airway hyperresponsiveness and inflammation cause reversible bronchoconstriction.
Chronic airway inflammation and/or alveolar destruction produce fixed obstruction and air trapping.
Spirometry reversibility (at least 12 percent and 200 mL FEV1 improvement post bronchodilator), normal-to-elevated DLCO, peripheral eosinophilia, elevated FeNO above 50 ppb, and methacholine challenge triggering bronchoconstriction at low doses support asthma.
Persistent post-bronchodilator FEV1/FVC below 0.70, hyperinflation with flattened diaphragms and increased AP diameter on chest X-ray, reduced DLCO when emphysema dominates, and either a smoking history or alpha-1-antitrypsin deficiency in a young nonsmoker support COPD.
The trap
Both wheeze and both lower FEV1/FVC below 0.70, so spirometry alone does not pick the disease. The deciding move is the post-bronchodilator response: FEV1 improvement of at least 12 percent and 200 mL names asthma; persistent obstruction names COPD. Asthma-COPD overlap exists in older smokers with reversibility, and treatment defaults to inhaled corticosteroid plus LABA when reversibility is significant.
Watch it explained
The repair move
For obstruction, ask reversibility, age, exposure story, and DLCO when emphysema is in the differential.
Try a free question
CoreA young patient with eczema has episodic nighttime wheezing and cough that improve markedly after bronchodilator. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Asthma. Atopy plus episodic reversible bronchoconstriction points to asthma.
Why the other choices are tempting
- B. COPD is chronic exposure-related fixed obstruction.
- C. Bronchiectasis causes chronic productive cough and airway dilation.
- D. PE causes sudden dyspnea and pleuritic pain with clot risk.
- E. Pneumonia causes infectious infiltrate and fever.
Flashcards
Tap a card to flip it.
What is the fastest separator for Asthma vs COPD?
Asthma: obstruction reverses at least 12 percent and 200 mL after a bronchodilator; COPD: largely fixed obstruction.
What clue should make you choose Asthma?
Episodic wheeze, cough, triggers, atopy, and reversible airflow obstruction.
Quick answers
What is the fastest way to tell Asthma from COPD?
Asthma: obstruction reverses at least 12 percent and 200 mL after a bronchodilator; COPD: largely fixed obstruction.
What is the key clue for Asthma?
Episodic wheeze, cough, triggers, atopy, and reversible airflow obstruction.
What is the key clue for COPD?
Chronic progressive dyspnea in a smoker or exposure history with less reversible obstruction.
What is the common trap with Asthma vs COPD?
Both wheeze and both lower FEV1/FVC below 0.70, so spirometry alone does not pick the disease. The deciding move is the post-bronchodilator response: FEV1 improvement of at least 12 percent and 200 mL names asthma; persistent obstruction names COPD. Asthma-COPD overlap exists in older smokers with reversibility, and treatment defaults to inhaled corticosteroid plus LABA when reversibility is significant.