Association of Preserved-Ratio Impaired Spirometry (PRISm) with All-Cause Mortality: A Longitudinal Cohort Study

Rationale: Numerous studies indicate that preserved-ratio impaired spirometry (PRISm) is associated with adverse clinical outcomes. However, the impact of PRISm severity, particularly in regard to forced vital capacity (FVC), on mortality risk remains unclear. Objectives: To determine whether PRISm was associated with mortality and to identify specific groups with particularly increased mortality rates. Methods: This retrospective study enrolled individuals aged >40 years who underwent comprehensive health screening at the Center for Health Promotion at Samsung Medical Center between 2003 and 2020. PRISm was characterized by a ratio of forced expiratory volume in 1 second to FVC of at least 0.7 and forced expiratory volume in 1 second <80% of predicted values. Participants were classified into three groups: normal lung function, PRISm with normal FVC, and PRISm with low FVC (FVC <80% predicted). We compared all-cause mortality rates using the Kaplan-Meier method and the Cox proportional hazard ratio model. Results: Among 106,458 individuals, 86,208 exhibited normal lung function, 6,249 had PRISm with normal FVC, and 14,001 had PRISm with low FVC. Over a median follow-up of 10.1 years, 2,219 participants died. Individuals with PRISm experienced a higher cumulative mortality rate compared with those with normal lung function (39 vs. 16 per 10,000 person-years; adjusted hazard ratio, 1.43; 95% confidence interval [CI], 1.31-1.56). The fully adjusted hazard ratios for all-cause mortality in PRISm with normal and low FVC were 1.25 (95% CI, 1.03-1.52) and 1.47 (95% CI, 1.33-1.62) relative to those with normal lung function, respectively. Conclusions: PRISm is associated with an increased risk of death, particularly when accompanied by low FVC.