Association Between Carbon Monoxide Intoxication and Incidence of Ischemic Stroke: A Retrospective Nested Case-Control Study in South Korea

Objectives Severe neurological sequelae occur in patients with carbon monoxide (CO) intoxication; however, whether the latter increases the long-term risk of developing ischemic stroke is unclear. We investigated the association between CO intoxication and ischemic stroke using data from the Korean National Health Information Database. Materials and Methods We performed a retrospective, nested case-control study of 27,984 individuals treated for CO intoxication and 27,984 sex- and age-matched controls. Initially, we calculated the overall incidence and hazard ratio (HR) of ischemic stroke using conditional logistic regression. Thereafter, we calculated the incidences and HRs according to covariates and follow-up periods. Results The CO intoxication group had a significantly higher risk of developing ischemic stroke than the control group (adjusted HR 2.31, 95% CI [confidence interval] = 2.01–2.65). Male sex (adjusted HR 2.73, 95% CI = 2.23-3.34), age <40 (adjusted HR 3.53, 95% CI = 2.15-5.82), low income (adjusted HR 2.55, 95% CI = 1.56–4.15), comorbidities (adjusted HR 2.59, 95% CI = 1.48–4.52), and current smokers (adjusted HR 3.55, 95% CI = 1.67–7.60) had a higher risk of ischemic stroke. The risk of ischemic stroke was highest within 2 years after CO intoxication (adjusted HR 7.47, 95% CI = 2.76–20.26), and even >6 years after, the risk remained significantly higher than in the control group (adjusted HR 1.84, 95% CI = 1.53–2.20). Conclusions CO intoxication and the long-term risk of ischemic stroke are associated.