Comments on: “The 30-Day Risk of Sudden Death in Patients With Epilepsy: A 10-Year Population-Based Cohort Study”

Dear Editor,We read with interest the article by Fan et al. 1 on a retrospective, longitudinal cohort study to develop and validate a short-term prediction model for sudden death in patients with epilepsy using a nationwide dataset from Taiwan.Of 161,773 treatment events, 3,454 sudden deaths were identified (2.1%). 1 Factors associated with an increased risk of sudden death included older age, admission to the intensive care unit, chronic kidney disease, psychotic disorder, poor adherence to antiseizure medication (ASM), and recent intravenous ASM use. 1 It was concluded that improving ASM adherence and optimizing epilepsy treatment may reduce the risk of sudden death in these patients.1 The study is noteworthy, but some points require discussion.The first point is that no comprehensible definition of sudden death has been provided.1 The definition of sudden death as death within a period of 30 days after observation does not correspond to the commonly used definitions.2 Sudden death is usually defined as unexpected death due to cardiac causes (fatal arrhythmia) within one hour of the onset of symptoms, or as unexpected death occurring immediately or within minutes or hours due to causes other than violence.3 The definition of sudden death is crucial because different healthcare professionals may understand different things by this term.Why were ICD codes for identifying sudden death, such as R96.0 and R96.1, not used?The use of ICD-10 codes such as I46, I46.2, I46.8, I46.9, I49.0, I49.01, and R99 suggests that these patients were assumed to have died from cardiac arrhythmias.However, the causes of sudden death are more diverse and not limited to cardiac causes.In addition to cardiac causes, sudden death can also be caused by pulmonary embolism, severe asthma, ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, venous sinus thrombosis, epilepsy, sudden unexplained death in epilepsy, severe allergic reactions (anaphylaxis), animal bites, and complications from sepsis, acidosis, illicit drugs, or medications.4 The second point is that no autopsy data was included in the analysis.Since autopsy findings and postmortem toxicological examinations can be crucial in determining the underlying cause of sudden death, it would have been helpful to include autopsy data in the study.In particular, a brain autopsy can be helpful in determining whether death was due to a neurological or non-neurological cause.The third point is that no epilepsy classification was included in the analysis.1 According to the ILAE recommendation, epilepsy is classified using a three-step framework, starting with the type of seizure (focal, generalized, or unknown onset), followed by the type of epilepsy (focal, generalized, combined, or unknown), and finally the epilepsy syndrome and etiology (cause, e.g., structural or genetic).5 This system aids in diagnosis, treatment, and research by providing a structured approach to understanding and categorizing the disorder.