Assessing the severity of stable COPD

Assess the severity of chronic obstructive pulmonary disease (COPD) both at diagnosis and as part of ongoing monitoring and review. COPD severity assessment guides management of COPD, which follows a stepwise escalation of nondrug and drug interventions.

The severity of COPD is determined by:

symptoms—consider breathlessness, limitation on daily activities, cough and sputum production
exacerbation history—consider frequency and severity (exacerbations occur more frequently as COPD progresses)
typical lung function (spirometry findings)—however, spirometric thresholds are somewhat arbitrary and may not correlate with other criteria for severity.

Assess the severity of COPD when the patient is stable (preferably not within 4 weeks of an exacerbation). See Classification of stable COPD severity for classifications of COPD severity.

Table 1. Classification of stable COPD severity
	Mild	Moderate	Severe
Symptoms and exacerbation history	few symptoms breathless on moderate exertion daily activities minimally limited or unaffected cough and sputum production	breathless walking on level ground daily activities increasingly limited recurrent chest infections exacerbations requiring oral corticosteroids or antibiotics	breathless on minimal exertion daily activities severely limited exacerbations of increasing frequency and severity
Typical lung function [NB1]	FEV₁ 60 to 80% predicted	FEV₁ 40 to 59% predicted	FEV₁ less than 40% predicted
Note: COPD = chronic obstructive pulmonary disease; FEV₁ = forced expiratory volume in 1 second NB1: Spirometric thresholds are somewhat arbitrary, and may not correlate with other criteria for severity; however, they can be useful to give an indication of severity. Adapted with permission from: Yang I, Dabscheck E, George J, Jenkins S, McDonald C, McDonald V, et al. The COPD-X Plan: Australian and New Zealand Guidelines for the management of Chronic Obstructive Pulmonary Disease 2020, Version 2.61. Milton, QLD: Lung Foundation Australia; February 2020. [URL]

The COPD Assessment Test (CAT) is a validated questionnaire that can be useful as part of a comprehensive assessment of symptoms. The modified Medical Research Council (mMRC) dyspnoea scale is useful to assess breathlessness.

Also assess for comorbidities (eg ischaemic heart disease, depression, anxiety) and sequelae of COPD (eg hypoxaemia), which may require additional treatment.