Diagnostic considerations when COPD is a possibility
Consider the possibility of COPD as an alternative diagnosis or asthma-COPD overlap in patients with respiratory symptoms and any of the following risk factors:
- current smoking or history of smoking and age 35 years and over
- exposure to environmental tobacco smoke or other smoke
- age 55 years and over
- longstanding asthma.
If spirometry before and after bronchodilator demonstrates airflow limitation that is not completely reversible in an adult with risk factors for COPD, consider the possibility of COPD, even if the person has never smoked.
- How this recommendation was developed
Based on clinical experience and expert opinion (informed by evidence, where available), with particular reference to the following source(s):
- Abramson et al. 20123
If an adult has risk factors for COPD, spirometry before and after bronchodilator demonstrates airflow limitation that is not completely reversible, and other diagnostic tests do not confirm asthma, start a treatment trial with an inhaled corticosteroid and repeat spirometry 6–8 weeks later.
After the trial of inhaled corticosteroid treatment, the diagnosis of asthma is supported if pre-bronchodilator spirometry shows that airflow limitation has resolved, or if spirometry before and after bronchodilator demonstrates airflow limitation that is fully reversible.
- How this recommendation was developed
Based on clinical experience and expert opinion (informed by evidence, where available)
Identify patients with characteristics strongly favouring either asthma or COPD. If the diagnosis is unclear, consider referral to a specialist respiratory physician.
Note: It is clinically important to identify asthma features because, in patients with features of both asthma and COPD, treatment should include an inhaled corticosteroid to reduce risk of flare-ups, and the use of long-acting beta2 agonist or long-acting muscarinic antagonist without concomitant inhaled corticosteroid should be avoided to reduce risk of adverse effects.
- How this recommendation was developed
Adapted from existing guidance
Based on reliable clinical practice guideline(s) or position statement(s):
Abramson et al. 20123
- Risk factors for COPD
Smoking is the most important risk factor for COPD.3 Current national COPD guidelines recommend that COPD should be considered in all smokers and ex-smokers over 35 years, and in all patients with other smoking-related diseases.3
- exposure to environmental tobacco smoke
- occupational exposure to dusts and fumes
- exposure to biological dust, diesel exhaust
- exposure to smoke from biomass fuels
- genetic predisposition (alpha1 antitrypsin deficiency) interacting with environment (e.g. smoking)
Other risk factors for fixed (irreversible or incompletely reversible) airflow limitation include:1
- inadequate maximal lung function achieved in early life (e.g. due to untreated asthma or severe asthma in early childhood, premature birth, or bronchopulmonary dysplasia)
- longstanding asthma.
- Diagnosis of COPD
The main symptoms of COPD are breathlessness, cough and sputum production. Patients often attribute breathlessness to ageing or poor cardiopulmonary fitness. A persistent cough, typically worse in the mornings with mucoid sputum, is common in smokers. Other symptoms, such as chest tightness, wheezing, fatigue and airway irritability are common.3
- a history of smoking or exposure to other noxious agents
- post-bronchodilator FEV1/FVC < 0.7 (or < lower limit of normal) together with FEV1 < 80% of the predicted value.
- Coexisting asthma and COPD
There is a subgroup of patients with longstanding asthma who do not demonstrate reversible airflow limitation.5, 6 Asthma that begins later in life often shows a component of irreversible or incompletely reversible airflow limitation (also called ‘fixed airway obstruction’), due to airway remodelling and stiffening of the chest wall.7 The same may be seen in patients with a history of severe asthma in childhood.
Correspondingly, there is a subgroup of patients with COPD who demonstrate significant (though incomplete) bronchodilator response and meet the diagnostic criteria for variable airflow limitation in asthma.5, 6 Most patients with COPD show some reversibility of airflow limitation with bronchodilators,3 and the degree of reversibility can vary from visit to visit.8
Overlap of asthma and COPD is fairly common among older patients attending primary care:
- In a Dutch analysis of GP patient lists, approximately 10% of patients using an inhaled medication had both COPD and asthma as assessed by an independent pulmonologist.9
- In a Belgian survey of 26 GPs, 30% of patients with asthma and 38% with COPD had their diagnosis changed to the combination of asthma and COPD following re-examination.9
- In a New Zealand population study, over 50% of people older than 50 years with airflow limitation showed some degree of overlap of asthma and COPD.10
COPD is an important comorbidity and can lead to under-diagnosis of asthma in older people.1
In older people, COPD and asthma can be difficult to distinguish because both disorders have similar manifestations despite potentially different causes and underlying abnormalities.1
Current Australian guidelines for the diagnosis and management of COPD recommend referral to a specialist respiratory outpatient service for patients with a clinical diagnosis of COPD in whom asthma cannot be excluded.3
Risk factors for coexisting asthma and COPD include ageing, longstanding asthma, and smoking. The coexistence of incompletely reversible airflow limitation (characteristic of COPD) and increased airflow variability (characteristic of asthma) is common among people with respiratory symptoms aged 65 years and over, and even among those over 50 years.1, 5Close
- Is it asthma, COPD or both?
The main symptoms of chronic obstructive pulmonary disease (COPD) are breathlessness, cough and sputum production. Chest tightness, wheezing and airway irritability are also common. Patients often attribute breathlessness to ageing or poor cardiopulmonary fitness.3
The Global Initiative for Asthma (GINA) and Global Initiative Obstructive Lung Disease (GOLD) recommend the following stepwise approach for adults presenting with respiratory symptoms:12
- Identify whether the patient has clinical features of, or is at risk of, chronic airway disease. This may be suggested by the clinical history and physical examination.
- Identify features that favour a diagnosis of typical asthma or typical COPD. If several features of both are present, asthma-COPD overlap is likely.
- Perform spirometry to confirm airflow limitation.
- Start treatment, selected according to whether the assessment favoured the single diagnosis of asthma, the single diagnosis of COPD, or asthma-COPD overlap.
- Refer for specialist assessment and other investigations, if necessary.
- Definition of variable expiratory airflow limitation
Most of the tests for variable expiratory airflow limitation are based on showing variability in FEV1. While reduced FEV1 may be seen with many other lung diseases (or due to poor spirometric technique), a reduced ratio of FEV1 to FVC indicates airflow limitation.13 Normal FEV1/FVC values derived from population studies vary,14, 15 but are usually greater than:14
- 0.85 in people aged up to 19 years
- 0.80 in people aged 20–39 years
- 0.75 in people aged 40–59 years
- 0.70 in people aged 60–80 years.
In children, it is less useful to define expiratory airflow limitation according to a specific cut-off for FEV1/FVC ratio, because normal values in children change considerably with age.15
Some spirometers provide predicted normal values specific to age group. If these are available, a FEV1/FVC ratio less than the lower limit of normal (i.e. less than the 5th percentile of normal population) indicates airflow limitation.
Variable expiratory airflow limitation (beyond the range seen in healthy populations) can be documented if any of the following are recorded:
- a clinically important increase in FEV1 (change in FEV1 of at least 200 mL and 12% from baseline for adults, or at least 12% from baseline for children) 10–15 minutes after administration of bronchodilator
- clinically important variation in lung function (at least 20% change in FEV1) when measured repeatedly over time (e.g. spirometry on separate visits)
- a clinically important reduction in lung function (decrease in FEV1 of at least 200 mL and 12% from baseline on spirometry, or decrease in peak expiratory flow rate by at least 20%) after exercise (formal laboratory-based exercise challenge testing uses different criteria for exercise-induced bronchoconstriction)
- a clinically important increase in lung function (at least 200 mL and 12% from baseline) after a trial of 4 or more weeks of treatment with an inhaled corticosteroid
- clinically important variation in peak expiratory flow (diurnal variability of more than 10%)
- a clinically important reduction in lung function (15–20%, depending on the test) during a test for airway hyperresponsiveness (exercise challenge test or bronchial provocation test) measured by a respiratory function laboratory.
Patients referred to a respiratory function laboratory may be asked not to take certain medicines within a few hours to days before a spirometry visit.
A clinically important increase or decrease in lung function is defined as a change in FEV1 of at least 200 mL and 12% from baseline for adults, or at least 12% from baseline for children, or a change in peak expiratory flow rate of at least 20% on the same meter.16, 13 A clinically important increase in FVC after administering bronchodilator may also indicate reversible airflow limitation, but FVC is a less reliable measure in primary care because FVC may vary due to factors such as variation in inspiratory volume or expiratory time.
The finding of ‘normal’ lung function during symptoms reduces the probability that a patient has asthma, but a clinically important improvement in response to bronchodilator or inhaled corticosteroid can occur in patients whose baseline value is within the predicted normal range.
The greater the variation in lung function, the more certain is the diagnosis of asthma. However, people with longstanding asthma may develop fixed airflow limitation.
Reversibility in airflow limitation may not be detected if the person is already taking a long-acting beta2 agonist or inhaled corticosteroid.
Airflow limitation can be transient and does not necessarily mean that the person has asthma (e.g. when recorded during a severe acute infection of the respiratory tract). Ideally, airflow limitation should be confirmed when the patient does not have a respiratory tract infection. Reduction in lung function during a respiratory tract infection with improvement in lung function after its resolution, commonly occurs in people with asthma, but can also be seen in patients with COPD or in healthy people without either asthma or COPD.17,18Close
- Gibson PG, McDonald VM, Marks GB. Asthma in older adults. Lancet. 2010; 376: 803-813. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20816547
- Guerra S. Asthma and chronic obstructive pulmonary disease. Curr Opin Allergy Clin Immunol. 2009; 9: 409-16. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832909/
- Abramson MJ, Crockett AJ, Dabscheck E, et al. The COPD-X Plan: Australian and New Zealand guidelines for the management of chronic obstructive pulmonary disease. Version 2.34. The Australian Lung Foundation and The Thoracic Society of Australia and New Zealand, 2012. Available from: http://www.copdx.org.au/
- Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for the diagnosis, management and prevention of COPD. GOLD, 2013. Available from: http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html
- Gibson PG, Simpson JS. The overlap syndrome of asthma and COPD: what are its features and how important is it?. Thorax. 2009; 64: 728-735. Available from: http://thorax.bmj.com/content/64/8/728.full
- McDonald VM, Higgins I, Gibson PG. Managing older patients with coexistent asthma and chronic obstructive pulmonary disease. Drugs Aging. 2013; 30: 1-17. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23229768
- Reed CE. Asthma in the elderly: diagnosis and management. J Allergy Clin Immunol. 2010; 126: 681-7; quiz 688-9. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20673985
- Albert P, Agusti A, Edwards L, et al. Bronchodilator responsiveness as a phenotypic characteristic of established chronic obstructive pulmonary disease. Thorax. 2012; 67: 701-8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/22696176
- van der Molen T. Co-morbidities of COPD in primary care: frequency, relation to COPD, and treatment consequences. Prim Care Resp J. 2010; 19: 326-334. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20842323
- Weatherall M, Travers J, Shirtcliffe PM, et al. Distinct clinical phenotypes of airways disease defined by cluster analysis. Eur Respir J. 2009; 34: 812-818. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19357143
- Abramson M, Frith P, Yang I, et al. COPD-X Concise Guide for Primary Care. Lung Foundation Australia, Brisbane, 2016. Available from: http://lungfoundation.com.au/health-professionals/guidelines/copd/copd-x-concise-guide-for-primary-care/
- Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. GINA, 2016. Available from: http://ginasthma.org/
- Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005; 26: 948-968. Available from: http://erj.ersjournals.com/content/26/5/948
- National Heart Lung and Blood Institute (NHLBI) National Asthma Education and Prevention Program. Expert Panel Report 3: guidelines for the diagnosis and management of asthma. Full report 2007. US Department of Health and Human Services National Institutes of Health, Bethesda, 2007. Available from: http://www.nhlbi.nih.gov/health-pro/guidelines/current/asthma-guidelines/full-report
- Quanjer PH, Stanojevic S, Cole TJ, et al. Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations. Eur Respir J. 2012; 40: 1324-43. Available from: http://www.ncbi.nlm.nih.gov/pubmed/22743675
- Levy ML, Quanjer PH, Booker R, et al. Diagnostic Spirometry in Primary Care: Proposed standards for general practice compliant with American Thoracic Society and European Respiratory Society recommendations. Prim Care Respir J. 2009; 18: 130-147. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19684995
- Collier AM, Pimmel RL, Hasselblad V, et al. Spirometric changes in normal children with upper respiratory infections. Am Rev Respir Dis. 1978; 117: 47-53. Available from: http://www.ncbi.nlm.nih.gov/pubmed/619724
- Melbye H, Kongerud J, Vorland L. Reversible airflow limitation in adults with respiratory infection. Eur Respir J. 1994; 7: 1239-1245. Available from: http://www.ncbi.nlm.nih.gov/pubmed/7925901