Association of Preserved Ratio Impaired Spirometry (PRISm) with All-Cause Mortality: a longitudinal cohort study

<bold>Background:</bold> Growing bodies of literature have shown Preserved Ratio Impaired Spirometry (PRISm) is related to poor clinical outcomes. However, the impact of PRISm severity, especially based on FVC, on mortality risks was not fully elucidated. <bold>Methods:</bold> This retrospective study included subjects older than 40 years who underwent a comprehensive health screening exam between 2003 and 2020 at the Center for Health Promotion, Samsung Medical Center. PRISm was defined as FEV1/FVC ≥ 0.7 and FEV1 <80% predicted. Participants were categorized into three groups: normal lung function, PRISm with normal FVC, and PRISm with low FVC (FVC <80% predicted). The all-cause mortality rates were compared using the Kaplan-Meier method and Cox proportional hazard ratio model. <bold>Results:</bold> Among 106,458 individuals, 86,208 normal lung function, 6,248 PRISm with normal FVC, and 14,001 PRISm with low FVC were identified. During a median follow-up of 10.1 years, 2,219 were dead. Participants with PRISm had a higher cumulative mortality rate compared to those with normal lung function (39 vs. 16 per 100 person-years; adjusted HR 1.44, 95% CI 1.31–1.58). The fully-adjusted HRs for all-cause mortality in PRISm with normal FVC and with low FVC were 1.24 (95% CI 1.02–1.51) and 1.48 (95% CI 1.35–1.163) with a reference of those with normal lung function, respectively. This association was consistent in all subgroups analyzed, although the association between PRISm with low FVC and death was stronger in underweight/normal compared to overweight/obese. <bold>Conclusion:</bold> PRISm was associated with an increased risk of death, particularly when accompanied by low FVC.