Screening tool underperforms in identifying undiagnosed COPD among primary care patients
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Despite demonstrating high specificity, a screening tool “did not perform well” overall in identifying undiagnosed COPD among primary care patients, researchers found.
According to CDC data, more than 50% of adults with low pulmonary function were not aware that they had COPD in 2018.
Because of insufficient evidence supporting COPD screening in asymptomatic individuals, “identifying patients with respiratory symptoms has been suggested,” Fernando J. Martinez, MD, MS, a professor of medicine at Weill Cornell Medical College, and colleagues wrote in JAMA.
The researchers evaluated the feasibility of this approach through the COPD Assessment in Primary Care to Identify Undiagnosed Respiratory Disease & Exacerbation Risk (CAPTURE), a simple tool that utilizes five questions on symptoms and exposure in addition to peak expiratory flow rates with sex-specific thresholds. The screening process takes less than 1 minute to complete, according to a press release about the study.
CAPTURE screening was performed among 4,325 adults (median age, 61 years), 63% of whom were women. Of the participants, 44.6% had a history of smoking cigarettes, 13.2% currently smoked cigarettes and 18.3% reported having a prior asthma diagnosis or used inhaled respiratory medications.
Clinically significant COPD was defined by the screening as an individual having moderate airflow obstruction or the presence of acute respiratory illnesses within the last 12 months.
Martinez and colleagues found that of the 110 patients (2.5%) with undiagnosed but clinically significant COPD, 53 had a positive screening result. Overall, the CAPTURE screening tool was associated with a:
- sensitivity of 48.2% (95% CI, 38.6-57.9); and
- specificity of 88.6% (95% CI, 87.6-89.6).
For clinically significant COPD diagnoses, the positive predictive value (PPV) was 10% (95% CI, 7.6-12.8), and the negative predictive value (NPV) was 98.5% (95% CI, 98.1-98.9).
The researchers noted the high specificity was influenced by the high prevalence of respiratory symptoms among those with a normal spirometry result, while the sensitivity was impacted by the high proportion of participants with an airflow obstruction.
Overall, the study “demonstrates the challenge of identifying undiagnosed patients with COPD in primary care,” Martinez and colleagues wrote. They also highlighted several considerations for future efforts to improve the tool.
“Balancing sensitivity and specificity is important to maintaining PPV and NPV while considering implementation burden,” they wrote. “Improving sensitivity using the current questions would require more assessments of peak expiratory flow rate and more referrals for spirometry evaluation, which may introduce challenges in implementation of the screening tool in primary care.”
The researchers also suggested changing the definition of clinically significant COPD to one that would be “more congruent” with current COPD recommendations for treatment initiation.
Although the CAPTURE tool needs to be refined, the study still demonstrates “that there is a high degree of respiratory burden in primary care, and physicians need to ask about it and do the appropriate testing to determine if symptoms are driven by COPD or another process so that patients can get the right treatment,” study coauthor MeiLan K. Han, MD, MS, a professor of medicine in the division of pulmonary and critical care at the University of Michigan, said in the press release.
References:
- Basics about COPD. https://www.cdc.gov/copd/basics-about.html. Accessed Feb. 15, 2023.
- Martinez F, et al. JAMA. 2023;doi:10.1001/jama.2023.0128.
- Screening tool aims to help doctors diagnose more people with COPD. https://www.eurekalert.org/news-releases/979403?. Published Feb. 14, 2023. Accessed Feb. 14, 2023.
Perspective
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Valerie Press, MD, MPH, FACP, FAAP, SFHM, ATSF
This was a very well-designed study of an important topic — identifying patients with COPD through a screening process. The co-primary outcomes were sensitivity and specificity of the CAPTURE tool. The findings were that the CAPTURE tool had low sensitivity but high specificity. Screening for COPD had been challenging and this study further emphasizes the difficulty of identifying screening methods that can help lead to early diagnosis of COPD.
As a screening tool, the CAPTURE tool would serve as a first step toward diagnosis, which would require formal lung function testing. Further evaluation of how to improve the sensitivity of the CAPTURE screening tool is warranted, though due to the ease of use, utility of the tool already exists.
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