Carbon monoxide poisoning is associated with an increased risk of epilepsy and status epilepticus: a nationwide population-based cohort study conducted in the Republic of Korea between 2002-2021.

Introduction: Carbon monoxide poisoning may result in various neurological injuries, including acute symptomatic seizures. We aimed to investigate the long-term risk of epilepsy and status epilepticus in patients with previous carbon monoxide poisoning.

Methods: The study population was derived from the National Health Insurance Service database of the Republic of Korea between 1 January 2002 and 31 December 2021. We included adults with at least one documented visit to medical facilities because of carbon monoxide poisoning (International Classification of Diseases, Tenth Revision, code T58). Patients were matched, on the same index date, with controls, without a T58 code, for age, sex, insurance type, income level, and residence location in a 1:1 ratio. Follow-up continued until death, migration, or the end of the observation period (31 December 2021). The primary outcome was the incidence of epilepsy (codes G40 or R56) and status epilepticus (code G41).

Results: This study included 53,380 patients with carbon monoxide poisoning and 53,380 controls, with 44.2% women and a mean age of 45.7 years. The mean (±SD) follow-up period was 5.7 ± 4.3 years in the carbon monoxide poisoned group and 6.4 ± 4.4 years in controls. The overall risk of epilepsy (adjusted hazard ratio 2.60; 95% CI: 2.43-2.78; P < 0.001) and status epilepticus (adjusted hazard ratio 4.10; 95% CI: 2.84-5.92; P < 0.001) was significantly increased in the carbon monoxide poisoned group compared to controls. The risk of epilepsy and status epilepticus was increased in patients with previous carbon monoxide poisoning, regardless of sex, age or a history of stroke, neurodegenerative diseases, or central nervous system tumour or infection. However, in the subgroup analysis according to age, the highest risk of epilepsy and status epilepticus was observed in patients less than 40 years of age.

Discussion: In this population-based cohort study, previous carbon monoxide poisoning was associated with an increased risk of epilepsy and status epilepticus. The risk was more noticeable in patients aged less than 40 years. Further studies are needed to confirm such an association in other populations.

Conclusions: Previous carbon monoxide poisoning was associated with an increased risk of epilepsy and status epilepticus, particularly in the younger population. The long-term management of survivors of carbon monoxide poisoning should include monitoring for epilepsy and status epilepticus.