Screening opportunity gap in COPD evaluation after low-dose CT findings: implications for risk-based spirometry in primary care

Low-dose chest computed tomography (CT) frequently detects findings suggestive of chronic obstructive pulmonary disease (COPD). However, the pathway from CT detection to physiological confirmation remains poorly characterized in real-world clinical practice. This study evaluated follow-up pathways after CT findings suggestive of COPD and assessed whether simple clinical factors could identify individuals at high risk of airflow limitation.

This retrospective observational study analyzed data from a voluntary, self-paid, community-based low-dose chest CT screening program in Japan that was open regardless of age or smoking history. Among 34,425 examinations conducted from fiscal year 2015 through February 2025, 1,336 examinations referred for suspected COPD were analyzed. Follow-up pathways were categorized as no documented follow-up, follow-up without spirometry, and follow-up with spirometry. Two multivariable logistic regression models evaluated documented follow-up and spirometry use. Airflow limitation was defined as a post-bronchodilator FEV₁/FVC ratio < 0.70.

Among 1,336 examinations, 305 (22.8%) had no documented follow-up, 556 (41.6%) had documented follow-up without spirometry, and 475 (35.6%) had documented follow-up with spirometry. Among those who underwent spirometry, airflow limitation was identified in 298 (62.7%). Current smoking was associated with lower documented follow-up, whereas older age and greater cumulative smoking exposure were associated with spirometry use. Concurrent suspicion of lung cancer was associated with a lower likelihood of spirometry use. Airflow limitation rates increased according to simple clinical risk factors. Examinations with all three risk factors-age ≥ 70 years, pack-years ≥ 40, and respiratory symptoms-had an airflow limitation prevalence of 79.8%. Notably, 90 examinations without spirometry met these high-risk criteria.

In this community-based CT screening program, substantial gaps were observed in documented follow-up after referral for suspected COPD and subsequent spirometry use despite the high prevalence of airflow limitation among those tested. Simple clinical factors may help identify high-risk individuals and improve targeted spirometry use in routine clinical practice.