C2.5 COPD case finding

The US Preventive Services Task Force reviewed the evidence on population-based screening of asymptomatic adults for COPD using questionnaires or office-based screening pulmonary function testing from January 2000 to January 2015. The review found no direct evidence to determine the benefits and harms of screening or treatment in screen-detected populations. On this basis, widespread population screening of asymptomatic adults was not recommended (Guirguis-Blake 2016, U. S. Preventive Services Task Force 2016). No new subsequent studies (from the period January 1, 2015, to March 25, 2021) were identified in a targeted systematic review commissioned by the USPSTF, which aimed to update the evidence on the effectiveness of screening asymptomatic adults (Webber 2022) [evidence level I].

Though population-based screening is not recommended, a retrospective analysis of health data in Canada found that over 99% of people with COPD had incurred at least one visit in any of the previous 5 years prior to recording of the diagnosis (Johnson 2020). COPD is commonly undiagnosed, until presentation requiring a hospital admission. These studies highlight the potential for earlier diagnosis, and interventions.

Similarly, analysis of 4,484 COPD subjects in the ‘Genetic Epidemiology of COPD cohort’ demonstrated the potential of under-diagnosis and under-treatment of COPD in females compared to males (DeMeo 2018). The authors concluded that females are more susceptible to the effects of COPD than males with respect to symptom burden, including severity of dyspnoea, and exacerbation risk, especially in younger females. Further, retrospective data suggests that females are at higher risk of presenting with a moderate or severe exacerbation than men (Stolz 2019). A large study (29,678) of randomly selected residents of Copenhagen aged between 40 and 80 found 11% had FEV₁/FVC <0.70 and FEV₁ <80% of predicted on pre-bronchodilator spirometry. Treatable problems were identified in many of these participants, including smoking (45%), insufficient physical activity (12%), obesity (28%), undiagnosed hypertension (28%) and undiagnosed hypercholesterolaemia (48%) (Çolak 2022).

Simple lung function tools can assist practitioners in the case finding of individuals who have undiagnosed COPD. The devices measure the amount of exhaled air in the first 1 and 6 seconds of expiration (FEV₁, FEV₆) and calculate FEV₁/FEV₆, which is the ratio of the amount of air forcibly exhaled in the first second relative to the first 6 seconds. In a sample of over 800 non-COPD subjects at 45 years old from the Tasmanian Longitudinal Health Study cohort, lung function, particularly a low pre-bronchodilator FEV₁/FVC ratio in the lowest 10 percentile, was associated with a 36-fold increase chance of development of COPD by 53 years old (Tan 2024) [evidence level II]. This indicates that a low FEV₁/FVC ratio in this age group provides an early opportunity to identify those at particular risk of development of COPD in the following 8 years.

As an alternative of population-based screening, evidence supports case finding by targeted screening using tools assessing lung function, clinical risk, and symptom burden.

A systematic review and meta-analysis of 17 studies compared micro-spirometers, or two questionnaires, against post-bronchodilator spirometry, for accurately detecting COPD (Schnieders 2021) [evidence level I]. The overall area under the curve (AUC) of micro-spirometers was 0.84 (95% CI 0.80–0.89). For questionnaires the AUC for the COPD population screener (COPD-PS) questionnaire was 0.77 (95% CI 0.63–0.85) and the COPD diagnostic questionnaire (CDQ) was 0.72 (95% CI 0.64–0.78). Another review of 39 studies with a variety of case finding strategies including screening questionnaires (n=13), handheld flow meters (n=5) and direct invitation for diagnostic spirometry (n=30), found that active opportunistic case finding through primary care had greater chance of detecting undiagnosed cases of COPD compared with usual care, especially if targeting individuals at higher risk with pre-screening questionnaires (Haroon 2015). In a cluster-randomised controlled trial of general practices in the UK, routine practice identified fewer new cases of COPD, while an active targeted approach to case finding including mailed screening questionnaires before spirometry was found to be a cost-effective way to identify undiagnosed patients and had the potential to improve their health (Jordan 2016). A French randomised controlled trial in the primary care setting supported the utility of a symptom and risk factor questionnaire to identify patients who should be assessed with spirometry (Chapron 2023) [evidence level II]. These studies demonstrate the diagnostic yields of identifying patients who should undergo formal diagnostic assessment with spirometry using practice-led symptom questionnaires administered to patients clinically suspected to have COPD.

Lung Foundation Australia’s Position Paper: COPD case finding in community settings, https://lungfoundation.com.au/resources/copd-case-finding-position-paper/ recommends that previously undiagnosed individuals aged 35 years or older should be assessed with the symptom checklist, followed by a ‘COPD screening device’ with an FEV₁/FEV₆ cut-off < 0.75. Individuals with an FEV₁/FEV₆ ratio < 0.75 should undergo formal diagnostic spirometry. Symptomatic individuals with an FEV₁/FEV₆ ratio ≥ 0.75 should be encouraged to visit their general practitioner as they may be at risk of other diseases or lung conditions and may require more formalised testing.^[1]

Patients that are added to a COPD register because of a systematic screening programme (Haroon 2020) received significantly higher levels of appropriate clinical care. However, only one in five case-found patients who were registered in the database ever received such care. Case finding is only likely to improve clinical care if patients with newly identified disease are promptly added to an active primary care COPD register.

[1] Level of evidence could not be assigned due to heterogeneity