Undiagnosed but clinically significant chronic obstructive pulmonary disease (COPD) may be widespread in many low- and middle-income countries, according to a large international study led by researchers at University College London (UCL). But the study found that a short questionnaire combined with peak expiratory flow provides a simple and cost-effective way to identify people at high risk of COPD in these settings.
COPD, including emphysema and chronic bronchitis, affects more than 300 million people globally. It is the third leading cause of mortality worldwide, with around 3 million deaths from COPD each year.
However the burden of chronic lung disease is not shared equally around the world. Around 90% of deaths from COPD occur in low- and middle-income countries. Globally COPD is also a major risk factor for poorer COVID-19 outcomes.
Professor John Hurst, principal investigator on the study, told Medscape UK: "In contrast to studies in high-income settings, our results suggest that screening for COPD in low- and middle-income countries finds undiagnosed, yet clinically significant disease - arguing for a more proactive approach to respiratory care.
"Our findings support the accuracy and feasibility of using simple screening tools to identify people affected by COPD living in diverse low- and middle-income settings."
A Neglected Public Health Crisis
In high-income countries, COPD can be readily diagnosed using spirometry. The main risk factor for COPD in this population is smoking, and screen-detected disease is usually mild or moderate.
In poorer countries the situation is more complex. Additional risk factors include smoke from biomass fuels used for cooking or heating, and poverty-associated factors such as impaired lung development and tuberculosis.
Yet spirometry remains impractical as a screening tool in many resource-poor areas because of the need for equipment, training, and interpretation from skilled personnel. More cost-effective screening tools are needed in these settings to identify people who require further confirmatory testing.
Professor Hurst said: "The argument against screening for COPD in high-income countries is that you find really mild cases - and so the argument has filtered through that it’s just not worth screening for. We wanted to challenge that.
"We felt that if you go in to different settings where COPD can arise from poverty and pollution, then you might find significant disease. And that is just what we have found.
"This is a neglected public health crisis in low- and middle-income countries. The global health community must urgently address the challenge of chronic respiratory disease and the determinants and consequences of this, including poverty, pollution and multi-morbidity."
Screening Study Results
The study used three simple COPD screening tools: two consisted of a questionnaire and peak expiratory flow combined (COLA 6 and CAPTURE) and, a third, a questionnaire alone (LFQ). All the participants also received a post-bronchodilator spirometry test to independently assess the accuracy of the results.
The cross-sectional study included 10,709 adults aged 40 years or older in three distinct settings: semi-urban Bhaktapur in Nepal, urban Lima in Peru and rural Nakaseke in Uganda. Participants were recruited irrespective of symptoms and/or a prior diagnosis of COPD.
All three of the tools performed similarly and had reasonable sensitivity and specificity for identifying COPD. The tools were able to identify people with COPD with an accuracy ranging between 73.0% and 90.6%, depending on the tool used and location.
Screening was more accurate for identifying people with clinically important COPD (GOLD groups B to D), suggesting that these tools may be a viable way to screen for high-risk disease in low-resource settings.
Professor Hurst pointed out that 95.3% of participants with COPD in the study were previously unaware of the diagnosis: "It is alarming that a high percentage of screen-identified COPD cases were clinically important, had severe or very severe changes in lung function, and that most were unaware of their diagnosis despite the high prevalence of symptoms and lower quality of life."
The study authors emphasise that further research is needed to assess the feasibility of screening in other settings and whether implementation is associated with improved clinical outcomes. But there is clearly a need for a more proactive approach to identifying COPD globally.
"Action is needed," said Professor Hurst. "Addressing chronic non-communicable diseases in low- and middle-income settings, including chronic respiratory disease, requires co-ordinated action across clinicians and researchers, third sector organisations, policy makers, and research funders.
"Only by working together can we improve the lives of some of the most vulnerable people in our societies."
Siddharthan T, Pollard SL, Quaderi SA, et al. Discriminative Accuracy of Chronic Obstructive Pulmonary Disease Screening Instruments in 3 Low- and Middle-Income Country Settings. JAMA. 2022;327(2):151–160. doi:10.1001/jama.2021.23065. https://jamanetwork.com/journals/jama/article-abstract/2787909
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Cite this: Tom Broder. Simple Screening Test for COPD Could Reduce Global Burden of Undiagnosed Disease - Medscape - Jan 11, 2022.