Identifying high-risk smokers without airflow limitation using new COPD criteria: pooled analysis of two Japanese...

Recently proposed multidimensional chronic obstructive pulmonary disease (COPD) diagnostic criteria incorporate computed tomography (CT) findings and symptoms beyond airflow limitation. These criteria, developed using North American cohorts, require validation in Asian populations in which COPD phenotypes differ. We examined whether these criteria identify Japanese smokers at increased exacerbation risk, particularly those without airflow limitation.

This retrospective analysis pooled data from two prospective Japanese cohorts (Kyoto-Himeji and K-CCR) that included 517 smokers aged ≥40 years undergoing chest CT and COPD assessment test (CAT). The criteria included one major criterion (airflow limitation) and five minor criteria (emphysema [low attenuation area percent, LAA% ≥5 %], airway wall thickening [wall area percent ≥60 %], symptoms, dyspnea, and chronic bronchitis). COPD was defined as meeting the major criterion plus ≥1 minor criterion or ≥3 minor criteria alone. Negative binomial regression examined three-year exacerbation risk.

Among 517 smokers, 364 had major criteria COPD, 26 had minor criteria-only COPD, 40 had airflow limitation without meeting COPD criteria, and 87 had neither (non-COPD group). Exacerbation rates were 0.270, 0.259, 0.161, and 0.069 per person-year, respectively. Both COPD groups had a significantly greater exacerbation risk than the non-COPD group (adjusted IRR: 4.95 [95 %CI: 1.79-14.62] for minor criteria-only; 3.95 [2.06-7.79] for major criteria). Higher CAT scores and LAA % were independently associated with a greater exacerbation risk in patients with COPD.

The new multidimensional COPD criteria successfully identified Japanese smokers at increased exacerbation risk, including those without airflow limitation, supporting their applicability across different populations. Registered at UMIN (UMIN000028387).