Study: Spirometry important in COPD diagnosis
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The prevalence of undiagnosed COPD was high among a cohort of individuals participating in low-dose CT lung cancer screening, suggesting that the addition of spirometry to radiological findings would likely improve identification of those with COPD, new data in the Annals of the American Thoracic Society suggest.
For this study, the researchers evaluated 986 participants in the U.K.-based Lung Screen Uptake Trial in which different targeted invitation strategies could improve participation of high-risk, low-income individuals in low-dose CT screening for lung cancer.
“More than half of those attending a ‘lung health check’ as part of a prescreening assessment were found to have physiological parameters of airflow obstruction consistent with a diagnosis of COPD, while two-thirds did not report a prior diagnosis,” Samuel Janes, FRCP, MSc, PhD, head of the department of respiratory medicine at University College London’s Lungs for Living Research Centre, said in a press release. “This study highlights that, while the finding of emphysema was fairly common in this population of current or past heavy smokers who were at risk of lung cancer, the physiological changes of airway obstruction found through spirometry was the strongest signal of the presence of respiratory symptoms and thus potentially clinically relevant COPD.”
Janes and colleagues polled participants about current or recent respiratory symptoms, including cough or dyspnea within the previous 12 months, and whether they had a history of COPD, pneumonia, asthma and other comorbidities, such as coronary heart disease, hypertension and diabetes. The researchers categorized participants as having undiagnosed COPD if they had not reported a prior diagnosis of COPD, chronic bronchitis or emphysema but met the Global Initiative for Obstructive Lung Disease (GOLD) criteria using pre-bronchodilator spirometry. Thoracic radiologists specializing in the disease read participants’ CT scans and characterized COPD as none, mild, moderate or severe based on visual inspection of the images.
Results showed that 57% of all participants had COPD as measured using pre-bronchodilator spirometry. Of these, 67% had undiagnosed COPD according to the study definition. Emphysema was also common, found in 73% of patients with known COPD and 68% of those with undiagnosed COPD. Thirty-two percent of those with undiagnosed COPD, however, had no evidence of emphysema on low-dose CT.
The researchers found that more participants with known vs. undiagnosed COPD used inhalers and had symptoms such as persistent cough (63% vs. 33%; P < .001) and dyspnea (73% vs. 33%; P < .001), although comorbidities were common among all participants.
Additionally, the adjusted odds of respiratory symptoms were more significant for airflow obstruction than for emphysema, the researchers noted.
“Thirty-two percent of participants with airflow obstruction who did not report a prior diagnosis of COPD had no emphysema on their CT scan, while, conversely, individuals with emphysema did not always have airflow obstruction,” Mamta Ruparel, MBBS, BSc, MRCP, PhD, academic clinical lecturer at University College London’s Lungs for Living Research Centre, said in the release. “Based on our findings, reliance on CT alone to diagnose COPD risks missing individuals who may actually have this condition while overdiagnosing others. Since individuals at risk for lung cancer are also at risk for COPD, we recommend including spirometry in low-dose CT lung cancer screening programs in order to assist in making accurate diagnoses.” – by Melissa Foster
Disclosure: Ruparel reports she received support for the SUMMIT Study from GRAIL Inc., travel funding from Takeda and honorarium from AstraZeneca. Please see the study for all other authors’ relevant financial disclosures.