D30-10 Spirometric Transitions of Respiratory Function: A Two-year Retrospective Cohort From the Japanese Red Cross Kumamoto Study

Abstract Rationale This study evaluated the spirometric transitions of respiratory function categories and development of airflow limitation (AFL) in a Japanese population. Methods This retrospective observational cohort study included participants who underwent health checkups, including respiratory function tests, at the Japanese Red Cross Kumamoto Health Care Center. We analyzed 12,507 participants (7,497 men and 5,010 women) aged 20-89 years in 2020 (baseline survey) and conducted follow-up assessments in 2022. Participants were categorized into four respiratory function categories at baseline using prebronchodilation spirometry: normal spirometry (n = 10,910), mild AFL (n = 551), moderate-to-severe AFL (n = 427), and preserved ratio impaired spirometry (PRISm) groups (n = 619). We assessed the transition from the above four groups, including annual FEV1 decline (ml/year), white blood cell counts, and high-sensitivity C-reactive protein levels, over a two-year period. The annual FEV1 decline (ml/year) was compared across transition groups, including Normal→Mild AFL (n = 352), Normal→ Moderate-to-severe AFL (n = 50), Normal→PRISm (n = 240), Mild AFL→Moderate-to-severe AFL (n = 51), and PRISm→Moderate-to-severe AFL (n = 66), using the Normal→Normal group (n = 10,269) as the reference. The present study was approved by the Ethics Committee of Kumamoto University (approval no. 84; date, August 23, 2023) and the Japanese Red Cross Kumamoto Health Care Center. Results The prevalence of PRISm at baseline was 4.9% (2.6% among women and 6.5% among men). The rates of spirometric transition to moderate-to-severe AFL in the normal spirometry, mild AFL, and PRISm groups in a two-year period were 0.46%, 9.3%, and 10.7%, respectively. The annual FEV1 decline (ml/year) for Normal→Mild AFL, Normal→ Moderate-to-severe AFL, Normal→PRISm, Mild AFL→Moderate-to-severe AFL, and PRISm→Moderate to severe AFL groups were -64.8 (Standard Error (SE): 3.6, p = 0.002), -164 (SE: 13.9, p 0.001), -119.3 (SE: 4.5, p 0.001), -134.5 (SE:9.6, p 0.001), and -63.8 (SE:9.0, p = 0.975), respectively, compared with that in Normal→Normal group (-41.8, SE: 0.7). White blood cell counts and high-sensitivity C-reactive protein levels in both the Moderate-to-severe AFL and PRISm groups at baseline were significantly higher than those in the normal spirometry group. Conclusions The rate of spirometric transition to moderate-to-severe AFL in the PRISm group was similar to that in the Mild AFL group. PRISm was associated with systemic inflammation as well as moderate-to-severe AFL. Our findings suggest that the recognizing PRISm is crucial for preventing the development of AFL. This abstract is funded by: None