Association of long-term nitrogen dioxide exposure with death in ischemic stroke patients and effect modification of greenness
Objective This study aimed to investigate the association between long-term nitro-gen dioxide(NO2)exposure and the risk of death in ischemic stroke(ischemic stroke,IS)patients,as well as the modification of greenness on this association.Methods We conducted a longitudinal study on IS cases in 4 districts/counties in the northwest region of Shandong Province with relatively high NO2 con-centrations from 2013 to 2019.Participants were followed up until December 31,2019,or the date of death.A time-dependent Cox proportional risk model was used to assess the hazard ratio(HR)and its 95％CI for stroke-related death in IS patients per IQR increase in NO2.The exposure-response relation-ship between long-term NO2 exposure and the risk of IS patient mortality was fitted using a restricted cubic spline function.We then explored the effect modification role of greenness exposure by incorporating an interaction term between NO2 and normalized difference vegetation index(NDVI)levels.Finally,we con-ducted a series of sensitivity analyses and subgroup analyses based on different genders,age groups,and urban/rural areas.Results A total of 46 252 IS patients were included in the study and the annual mean concentration of NO2 in the 4 districts/counties from 2013 to 2019 was(43.30±1.32)μg/m3.The re-sults showed that the HR of death in IS patients were 1.22(1.15-1.29)for each IQR increase in NO2.The exposure-response relationship showed a non-linear relationship between long-term NO2 exposure and the risk of IS patient mortality.The results of the interaction were found to be statistically significant(Pnolinear=0.005)with HRs of 1.23(1.17-1.30),1.21(1.15-1.28),and 1.19(1.12-1.26)for each IQR of NO2 rise in patients with IS at the low,middle,and high levels of exposure to the greenness,respectively.Interaction effects between long-term NO2 exposure and greenness exposure was found across different gender and age groups,as well as in rural areas(all P＜0.05).Conclusions Long-term expo-sure to NO2 is considered a risk factor for mortality in IS patients,while greenness may potentially miti-gate this detrimental effect.
Ischemic strokeNitrogen dioxideGreennessLongitudinal study
NETL
NSTL
万方数据
