Association between Preserved Ratio Impaired Spirometry with mortality and long-term cardiovascular outcomes in Chinese adults

BackgroundTo examine the prevalence and characteristics of PRISm among Chinese individuals, as well as its association with future mortality and cardiovascular (CVD) outcomes. MethodsThis was a substudy of the Prospective Urban Rural Epidemiology (PURE) study, which recruited 40,279 individuals aged 35-70 years from 115 urban and rural communities in 12 provinces across China between 2005 and 2009. At baseline, participants were categorized into subgroups based on PRISm, airflow obstruction (AO), and normal spirometry. Follow-up was conducted every three years to obtain information on major cardiovascular events and mortality. Cox frailty proportional hazard regression was used to estimate the hazard ratios (HR) and 95% confidence interval (95%CI). ResultsThe baseline prevalence rates of PRISm, AO and normal spirometry were 29.3%, 8.5%, and 62.2% respectively. Over a median follow-up period of 11.9 years, 2,214 deaths, with 773 attributed to CVD, and 3,507 major CVD events were observed. After adjusting for potential confounders, individuals with PRISm, comparing to those with normal spirometry, exhibited significantly elevated risks of all-cause mortality (HR 1.42, 95%CI [1.29, 1.58]), CVD mortality (HR 1.35, 95%CI [1.14, 1.60]), major CVD events (HR 1.16, 95%CI [1.07, 1.25]), myocardial infarction (HR 1.34, 95%CI [1.15,1.56]), and heart failure (HR 2.02, 95%CI [1.46, 2.79]). ConclusionsPRISm, a frequently observed result in spirometry among the general Chinese population, exhibits a substantial association with long-term all-cause mortality, CVD mortality, major CVD events. Further investigation is warranted to comprehensively compared the underlying pathophysiologic connection between PRISm and CVD as well as mortality. What is already known on this topicPRISm is considered a transient state with higher transition rates to both normal and obstructive spirometry, often indicating progression to COPD, which is associated with increased respiratory symptoms, diminished quality of life, and a higher risk of cardiovascular events and all-cause mortality. Given the limited understanding of PRISm, there are several studies on the association between PRISm and health outcomes have been carried out in different populations since the concept of PRISm was introduced in 2014. Longitudinal studies based on population cohorts such as COPDGene, UK Biobank, Rotterdam, and NHLBI have shown that PRISm is associated with an increased risk of all-cause mortality and adverse cardiovascular outcomes, with similar results found in a study based on a Japanese population. Lung function differs substantially between races and regions. Most of the existing PRISm-related studies are based on populations in developed countries such as Europe and the United States, and the conclusions of these studies should not be directly generalized to East Asian populations, including China. Currently, there is only two studies based on a Japanese and Korean aimed at exploring the relationship between PRISm and all-cause mortality and adverse cardiovascular outcomes, but the sample size of these study is relatively small, and the statistical power of the conclusions is relatively limited. What this study addsThis is the first longitudinal study examining the association of PRISm with the risk for all-cause mortality and adverse cardiovascular outcomes in a general Chinese population. The results showed that the prevalence of PRISm in the general Chinese population is 29.3%, which is significantly higher than previous studies. Compared to individuals with normal spirometry, the population with baseline PRISm had a significantly increased risk of all-cause mortality, CVD mortality, myocardial infarction (MI), and heart failure (HF), and showed a trend towards higher risk than those with baseline airflow obstruction (AO, although no statistically significant difference was observed). How this study might affect research, practice or policyOur findings support that the early prevention, diagnosis, and intervention of PRISm may offer an important strategy to alleviating the high CVD burden in China.