Simple Screening Tools Could Help Identify COPD in Low-, Middle-Income Countries

By Marilynn Larkin

January 21, 2022

NEW YORK (Reuters Health) - Three screening tools for chronic obstructive pulmonary disease (COPD), based on questionnaires and peak expiratory flow (PEF), were feasible to administer in low- and middle-income countries (LMICs) and showed good discriminative accuracy in a cross-sectional analysis.

In high-income countries, COPD generally is caused by smoking and diagnosed by spirometry. In LMICs, the picture is more complicated because important causes include household air pollution and impaired lung growth or lung damage, Dr. John Hurst of University College London and colleagues explain in JAMA. Spirometry is often unavailable, and many cases go undiagnosed.

"The high prevalence of clinically significant disease was surprising, and emphasizes the need for a greater focus on chronic respiratory disease," Dr. Hurst told Reuters Health by email. "The performance of the three tools had not previously been tested at the population level in diverse LMIC settings."

"We thought they would perform reasonably well, and they did," he added.

The team studied close to 11,000 adults (mean age 56.3; 50%, women) in three countries: semiurban Bhaktapur, Nepal; urban Lima, Peru; and rural Nakaseke, Uganda. Thirty-five percent had ever smoked and 30% were currently exposed to biomass smoke.

Three screening tools were tested and assessed against a reference standard diagnosis of COPD using post-bronchodilator spirometry:

  • COPD Assessment in Primary Care to Identify Undiagnosed Respiratory Disease and Exacerbation Risk (CAPTURE): range, 0-6; high risk indicated by a score of 5 or more or score 2-5 with low PEF (<250 L/min for females and <350 L/min for males); also uses PEF.

  • COPD in LMICs Assessment questionnaire (COLA-6): range, 0-5; high risk indicated by a score of 4 or more; also includes a measure of pulmonary expiratory flow (PEF).

  • Lung Function Questionnaire (LFQ): range, 0-25; high risk indicated by a score of 18 or less; does not include PEF.

The primary outcome was discriminative accuracy of the tools in identifying COPD as measured by area under receiver operating characteristic curves (AUCs).

The unweighted prevalence of COPD was 18.2% in Nepal; 2.7% in Peru; and 7.4% in Uganda. Among 1,000 COPD cases, 49.3% had clinically important disease; 16.4% had severe or very severe airflow obstruction (forced expiratory volume in 1 second <50% predicted); and 95.3% were previously undiagnosed.

The AUC for the screening instruments ranged from 0.717 for LFQ in Peru to 0.791 for COLA-6 in Nepal. Sensitivity ranged from 34.8% for COLA-6 in Nepal to 64.2% for CAPTURE in Nepal.

The mean time to administer the tests was 7.6 minutes, and data completeness was 99.5%.

Dr. Hurst said, "We need to show that the screening tools can be implemented in routine LMIC healthcare settings; that informing people that they have COPD leads to meaningful changes in outcomes; and thus, that screening is beneficial not just to individuals, but to the population in that particular context."

Commenting on the study by email, Dr. Eric Cioe-Peña, Director of Global Health for Northwell Health in New Hyde Park, New York, told Reuters Health, "Like any global health initiative, if there is a test that either demonstrates a major burden of disease that was previously unseen, or allows for early intervention, treatment and prevention strategies that can be incorporated into an LMIC's strategic plan for health, then there is huge value."

"The discussion about available resources once you have a positive screening test is real, and the availability of spirometry is variable not only in the three countries mentioned but also in LMICs in general," he said. "The concern over the false positive rate is a real one."

Dr. Jamuna Krishnan, a pulmonary critical care physician at Weill Cornell Medicine in New York City, also commented by email. "Though not the goal of the study, one important piece of data is that only 50.5% of the individuals with COPD had a current or past history of tobacco smoking. It highlights that while smoking is an important risk factor to consider, the absence of tobacco smoking should not rule out COPD."

"Once a diagnosis of COPD is established, there are lots of interventions and support that can be established for patients," she said. "There is also a need for further research to provide targeted therapy to prevent future lung function decline."

SOURCE: https://bit.ly/3FLVRaV and https://bit.ly/3FG1580 JAMA, online January 11, 2022.

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