COPD is characterised by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases and influenced by host factors including abnormal lung development. Performance and interpretation of spirometry should be based on clinical suspicion of airway disease in a patient with suggestive symptoms and exposures, where a medical history has been taken and examination performed. Targeting treatment to address outcomes that are most important to the individual is important as is ongoing assessment of therapy and cessation where an intervention has provided no benefit. Pulmonary rehabilitation is a vital component of COPD care but is underutilised. Indications for referral include: diagnostic uncertainty; suspected severe COPD; a rapid decline in FEV₁; a need for oxygen therapy assessment; onset of symptoms under 40; onset of cor pulmonale, assessment for long-term nebuliser therapy; dysfunctional breathing and symptoms disproportionate to lung function deficit. Regular follow-up is crucial and provides the opportunity to assess symptoms, exacerbations and comorbidities. The MRC dyspnoea score is useful to assess breathlessness and the COPD Assessment Tool score to assess health status.

The current Global Obstructive Lung Disease (GOLD) definition¹ describes COPD as a common, preventable and treatable disease that is characterised by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases and influenced by host factors including abnormal lung development. Significant comorbidities may have an impact on morbidity and mortality.

There is a clear emphasis on the presence of airflow obstruction, determined by spirometry, and exposure to noxious inhalants, typically tobacco smoke.

However, there is now a much clearer understanding about the development of airflow obstruction from recent studies in children and adolescents.²

The core finding from this research is the presence of a group of adults with physiologically defined COPD, not because of an accelerated decline in lung function from inhalants such as cigarette smoke, but because of early life events in utero and in childhood.

This cohort already had impaired lung function (small lungs) as they entered adulthood. This has an important impact on diagnosis and interpretation of spirometry.

Spirometry is used to diagnose COPD in people with suggestive symptoms and risk factors. There is an evidence base spanning more than 20 years which shows the positive impact of spirometry on diagnosis, and the inaccuracy of diagnosis without it.³

NICE guidance emphasises the role of spirometry in the diagnosis of COPD,⁴ and also asthma.⁵

However, the recent national COPD audits found that 48% of people hospitalised with ‘COPD’ in England and Wales had no record of spirometry and 13% who had had spirometry performed previously did not have COPD.⁶

COPD is characterised by the presence of post-bronchodilator airflow obstruction though there is a lack of consensus about how to define airflow obstruction. NICE recommends using the lower limit of normal, typically using Global Lung Initiative 20127 reference values. In contrast, GOLD recommends using a fixed FEV₁/FVC ratio.

There are pros and cons to each approach. These are summarised in table 1.

It is obviously beneficial to have local/regional agreement as to which method to use so there is geographical consistency.

What is crucial is that performance and interpretation of spirometry should be based on clinical suspicion of airway disease in a patient with suggestive symptoms and exposures, where a medical history has been taken and examination performed. Deviation from this well established practice is not infrequently the cause of diagnostic uncertainty.

Equally important is the need for spirometry to be performed only by individuals who are trained and in the UK that should be to standards set by the Association for Respiratory Technology & Physiology.

Differential diagnoses

Asthma is more challenging to diagnose and the core investigation is again spirometry, but with reversibility testing.

Reversibility testing is not required to diagnose COPD,4 but in light of the significant overlap in symptoms between COPD and asthma and the often uncertain pretest diagnosis, many practitioners perform spirometry and reversibility as a first diagnostic test for all patients. There are pragmatic arguments to carrying out FeNO testing alongside spirometry as part of a ‘one stop’ system.

Table 2 shows the differential diagnoses of COPD, key findings on clinical assessment and differences in diagnostics.

Treatment

There are a wide variety of treatments used to treat COPD; some reduce symptoms, others reduce future risk and some reduce both. Treatment goals for patients with COPD are shown in table 3.

Targeting treatment to address outcomes that are most important to the individual is clearly important as is ongoing assessment of therapy and cessation where an intervention has provided no benefit. In particular, the benefit of certain treatments is less clear-cut in many people with COPD and when commencing these it is important to assess benefit and discontinue if this is not seen.

Current COPD treatments are summarised in table 4.

Inhaler therapy is based on NICE guidance4 and this is shown in figure 1.

Pulmonary rehabilitation

Pulmonary rehabilitation is a vital component of COPD care but is underutilised8; this area has been reviewed previously in detail in this publication.⁹

Delivery of pulmonary rehabilitation services has been impacted further by the COVID-19 pandemic with restriction of face to face training. However, it is highly cost effective and we know from the national pulmonary rehabilitation audit6 that when a pulmonary rehabilitation programme is completed the benefit is significant as shown in figure 2.

To address poor uptake and completion as well as deliver future pulmonary rehabilitation services a variety of methods of delivery will be needed; this has been described as a menu of options.¹⁰ These could include face to face training, remote monitored and web or app based programmes. Over the next few years, more evidence will emerge about the effectiveness of various delivery methods.

Pulmonary rehabilitation programmes must include exercise training, education and self-management. Pulmonary rehabilitation in the 28 days after hospitalisation reduces rehospitalisation and improves symptoms.¹¹

Referral

The vast majority of COPD care is not delivered in hospital but in the community. However, there are situations where referral for specialist advice is warranted, and this advice is increasingly provided as part of integrated community respiratory services. NICE recommends referral for specialist advice in the situations shown in table 5.⁴

Follow-up

Regular follow-up is important and, in the UK, this is typically performed at least annually for those recorded as having COPD listed on a primary care COPD register. The review provides the opportunity to assess symptoms, exacerbations and comorbidities.

The MRC dyspnoea score is useful to assess breathlessness and the CAT (COPD Assessment Tool) score to assess health status. Frequency of acute exacerbations should be noted on the primary care record and reviewed. Oxygen saturations, assessed at a time of clinical stability, should be measured to assess the need for oxygen.

Review of smoking status and vaccination history allows these areas to be targeted. Inhaler technique should be checked and choice of inhaler should be reviewed annually which necessitates face to face rather than remote review. The latter is challenging in light of COVID-19 but vital to the patient.

Metered-dose inhalers are the source of a major part of the NHS carbon footprint whereas dry powder inhalers do not have the same impact. A British Thoracic Society statement addresses this area.¹² However, the most important recommendation is that patients need to be prescribed an inhaler that they can and will use.

Annual spirometry is recommended as part of NICE⁴ and GOLD² guidance but this has been challenging due to the impact of the pandemic on respiratory diagnostic services; both the large backlog of tests accumulated when spirometry was not deliverable and the reduced capacity associated with testing restrictions.

Pragmatically, some spirometry services have opted to prioritise diagnostic tests ahead of routine follow-up tests in the short to medium term.

Greater integration, less duplication and better information sharing are all high on the agenda and can deliver significant benefit for people with COPD and their carers.