Interaction between ambient CO and temperature or relative humidity on the risk of stroke hospitalization: A medical records-based study in Ningxia, China, 2014-2019

Abstract

Abstract Background Although the independent effects of ambient CO and temperature or humidity on stroke have been supported by much evidence, it is still unclear where there is an interaction between these factors and who is sensitive populations for these. Methods We extracted information of hemorrhagic or ischemic stroke from the homepage of the discharge medical records. The ambient CO and temperature, humidity were collected from National Monitoring Center. A generalized additive model, the double contamination model was used to analyze the independent effects of CO and temperature or humidity on stroke hospitalization.The bivariate response surface model and stratified analysis were used to evaluate the interaction between these factors. Findings High temperature and CO levels had synergistic effects on hemorrhagic stroke(RERI = 0.05, 95% CI: 0.033 ~ 0.086) and ischemic stroke(RERI = 0.035, 95% CI: 0.006 ~ 0.08). Low relative humidity and CO were synergistic in hemorrhagic stroke (RERI = 0.192,95% CI: 0.184 ~ 0.205), but in ischemic stroke, low relative humidity and CO were synergistic only in the elderly group (RERI = 0.056,95%CI: 0.025 ~ 0.085). Interpretation Exposure to CO increases the risk of hospitalization related to hemorrhagic and ischemic strokes. CO and temperature or humidity interact with risk of stroke hospitalization with sex and age differences.