Prognostic Value of Trajectory Linearity in Rapid Lung Function Decline: Insights From a Community-Based Prospective Cohort

초록

Rationale Rapid lung function decline (RLFD) has been identified as a risk factor for poor prognosis. However, among rapid decliners, the prognostic significance of the linearity of lung function trajectory remains unclear. Methods We used the Ansan-Ansung cohort, a population-based prospective cohort study. We analyzed trajectory patterns using consecutive lung function measurements over 12 years. RLFD was defined as the annual forced expiratory volume in 1 s (FEV1) decline rate < -60 mL/year. Linearity was quantified as the absolute value of the area under the receiver operating characteristic curve (AUROCabs)-the absolute difference between the areas above and below the straight line connecting the first and last lung function measurements. Within rapid and non-rapid decliners separately, trajectories were classified as nonlinear when this value exceeded the median and linear when it was below. The outcome was all-cause mortality, and the risk was assessed using multivariable Cox proportional hazards regression analysis. Results A total of 6,604 individuals were followed for 20.2 years. Rapid decliners with low AUROCabs (linear trajectory) had an increased risk of mortality compared with non-rapid decliners with low AUROCabs (adjusted hazard ratio [aHR] = 1.81, 95% confidence interval [CI] = 1.45-2.26). However, when AUROCabs was high (nonlinear trajectory), the mortality risk was not significantly increased, even among rapid decliners (aHR = 1.23, 95% CI = 0.94-1.61). Conclusion Among rapid decliners, low AUROCabs, indicating a more linear trajectory, was associated with a higher mortality risk. Trajectory linearity may therefore be a useful prognostic marker in this population.