What is COPD and how is it classified?

COPD (Chronic Obstructive Pulmonary Disease) is a progressive lung condition causing persistent airflow limitation. The GOLD classification stages it 1–4 based on FEV1 percentage: GOLD 1 (mild, ≥80% predicted), GOLD 2 (moderate, 50–79%), GOLD 3 (severe, 30–49%), and GOLD 4 (very severe, <30%).

What blood tests are done for COPD?

Key tests include full blood count (to detect polycythaemia from chronic hypoxia), ABG (arterial blood gas for oxygen/CO2 levels), alpha-1 antitrypsin level (to rule out hereditary deficiency), and CRP/ESR during exacerbations to assess infection or inflammation.

How is COPD different from asthma?

COPD is largely irreversible airflow obstruction caused mainly by smoking, while asthma involves reversible airflow limitation usually triggered by allergens or irritants. A bronchodilator reversibility test (spirometry before and after salbutamol) helps distinguish them: COPD shows <12% or <200 mL improvement; asthma typically shows ≥12% improvement.

COPD cannot currently be cured, but progression can be slowed. Smoking cessation is the single most effective intervention at any stage. Bronchodilators, inhaled corticosteroids, pulmonary rehabilitation, and in severe cases long-term oxygen therapy improve quality of life and reduce exacerbation frequency.

COPD: Chronic Obstructive Pulmonary Disease & Diagnosis

COPD Staging (GOLD Classification)

GOLD Stage	Severity	FEV₁ (% predicted)	Typical Symptoms
GOLD 1	Mild	≥80%	Cough, mild breathlessness on exertion
GOLD 2	Moderate	50–79%	Increased breathlessness; may limit activities
GOLD 3	Severe	30–49%	Significant breathlessness; frequent exacerbations
GOLD 4	Very severe	<30%	Very severe breathlessness; poor quality of life

Treatment Ladder

Stop smoking: the only intervention that slows disease progression
SABA (salbutamol) or SAMA (ipratropium): short-acting bronchodilators for relief
LABA + LAMA (dual long-acting bronchodilator): e.g. tiotropium + olodaterol
Triple therapy: LABA + LAMA + ICS, for frequent exacerbations, high eosinophil count
Pulmonary rehabilitation: 8–12 weeks; reduces hospitalisations and improves QoL
Long-term oxygen therapy (LTOT): for resting SpO₂ <92% on air for >15 hours/day

Pulmonary Rehab Is as Effective as DrugsNHS pulmonary rehabilitation reduces breathlessness, improves exercise tolerance, and reduces hospital admissions by 30–50%. It's free on the NHS: ask your GP for a referral.

COPD Exacerbation Warning SignsIncreased breathlessness, change in sputum colour (green/yellow = infection), worsening cough. Action plan: rescue antibiotics and prednisolone at home if trained. Hospital if SpO₂ <88% or not improving.

Is COPD the same as emphysema?

Emphysema is one component of COPD: destruction of alveoli reducing gas exchange surface. COPD also includes chronic bronchitis (airway inflammation with productive cough). Most patients have both.

Can you get COPD without smoking?

Yes. Alpha-1 antitrypsin deficiency (genetic), occupational exposure (dust, chemicals), and biomass fuel exposure (cooking fires) cause COPD in non-smokers. About 15% of COPD occurs in never-smokers.

What relieves COPD breathlessness?

Inhaled bronchodilators (LABA/LAMA), pulmonary rehabilitation, breathing techniques (pursed-lip breathing, pacing), oxygen if hypoxic, and low-dose opiates (morphine) for refractory dyspnoea.

How is a COPD exacerbation treated?

Increased bronchodilator use; prednisolone 30 mg for 5 days; antibiotics if sputum is purulent. Hospital if severe (SpO₂ <88%, confusion, unable to complete sentences, failure to respond to home treatment).

References

The clinical information on this page is based on peer-reviewed sources indexed in PubMed, the biomedical literature database of the US National Library of Medicine.

MacLeod M, Papi A, Contoli M, et al.. Chronic obstructive pulmonary disease exacerbation fundamentals: diagnosis, treatment, prevention and disease impact. Respirology. 2021;26(6):532-551. doi:10.1111/resp.14041 · PMID 33893708

References

Sources cited on this page. PubMed links open the original abstract.

Global Initiative for Chronic Obstructive Lung Disease. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: 2017 Report. GOLD. 2017;:1–148. PMID 28286592

FEV1/FVC ratio – the cornerstone of COPD diagnosis

COPD cannot be diagnosed on symptoms or X-ray alone – spirometry (lung function testing) is required. The key diagnostic ratio is FEV1/FVC: the forced expiratory volume in one second divided by the total volume exhaled in a full forced breath (forced vital capacity). In healthy lungs, FEV1 is at least 70% of FVC. In COPD, airflow obstruction (narrowed, damaged airways and loss of lung elastic recoil) reduces FEV1 disproportionately – so the FEV1/FVC ratio falls below 0.70 (or 70%) after bronchodilator use.

This post-bronchodilator ratio distinguishes COPD from asthma: asthma causes reversible obstruction (FEV1 improves significantly after bronchodilator); COPD causes fixed, largely irreversible obstruction. GOLD (Global Initiative for Chronic Obstructive Lung Disease) staging grades COPD severity by FEV1 as a percentage of predicted:

GOLD 1 (Mild): FEV1 ≥ 80% predicted
GOLD 2 (Moderate): FEV1 50–79%
GOLD 3 (Severe): FEV1 30–49%
GOLD 4 (Very severe): FEV1 < 30%

Blood tests in COPD assessment and exacerbations

FBC: COPD causes secondary polycythaemia (high red cell count) in patients with chronic hypoxaemia – the body's response to insufficient oxygen. A haematocrit above 55% (males) or 50% (females) suggests this. Conversely, anaemia worsens breathlessness and functional capacity and is common in COPD patients with systemic inflammation.
CRP and procalcitonin: During COPD exacerbations, CRP helps distinguish bacterial from viral causes. Procalcitonin above 0.25 µg/L suggests bacterial infection and supports antibiotic prescribing; below 0.1 suggests a viral trigger and antibiotics can often be withheld. NICE guidance (NG115) endorses procalcitonin-guided antibiotic decisions in hospitalised COPD exacerbations.
Alpha-1 antitrypsin (AAT): A1AT deficiency is a genetic disorder causing early-onset, predominantly lower lobe emphysema in non- or light smokers. It affects approximately 1 in 3000–5000 people. AAT serum level and genotyping (Pi*ZZ, Pi*MZ) should be checked in COPD patients under 45, non-smokers with COPD, or those with a family history of early emphysema. AAT augmentation therapy is available for confirmed deficiency with established emphysema.
BNP or NT-proBNP: Right heart failure (cor pulmonale) is a complication of severe COPD. Raised NT-proBNP (above 300 pg/mL) in a breathless COPD patient warrants echocardiography to assess right ventricular function and pulmonary artery pressure.

COPD: Causes, Spirometry Staging & Treatment

COPD Staging (GOLD Classification)

Treatment Ladder

References

References

FEV1/FVC ratio – the cornerstone of COPD diagnosis

Blood tests in COPD assessment and exacerbations

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