Forced expiratory volume in 1 s, Forced vital capacity, General population, All-cause mortality, Non-linear relationship, Diseases of the respiratory system, RC705-779

Abstract Background The ratio of the forced expiratory volume in 1 s (FEV1) to the forced vital capacity (FVC) is an essential tool for the diagnosis of chronic obstructive pulmonary disease (COPD). However, the relationship between levels of FEV1/FVC and mortality in the general population remains unclear, particularly its non-linear relationship. Therefore, we aimed to explore the association between the FEV1/FVC and all-cause mortality in the general population. Methods The data of participants included in the National Health and Nutrition Examination Survey (1988–1994 and 2007–2012 cycles) were analyzed. Participants aged ≥20 years, who were not pregnant, who underwent quality-controlled lung function tests, and with follow-up data on mortality status were enrolled. The study outcome was all-cause mortality. The participants were grouped by FEV1/FVC ratio in 0.10 increments. Cox proportional-hazards models were used to estimate the association between the FEV1/FVC ratio and all-cause mortality before and after confounder adjustment. Non-linear associations were explored using restricted cubic spline curves. Results Overall, 25,501 participants were included. During the median follow up of 308 months, 6431 (25.2%) deaths were recorded. Among all participants, the mean age is 46.3 years, and 48.7% of which were male. In unadjusted model, individuals with an FEV1/FVC ratio