Epilepsy diagnosis after Covid-19 : A population-wide study

Background: We aimed to investigate whether SARS-CoV-2 infection was associated with an increased risk of incident epilepsy. Methods: National register-based matched study. Verified cases of SARS-CoV-2 infection were acquired from the system for communicable disease surveillance in Sweden (SmiNet) and linked to data from the National Patient Register (NPR) and Cause of Death register in Sweden. Cases and non-infected controls were compared using a Cox proportional hazards model. Results: A total of 1,221,801 SARS-CoV-2 infected patients and 1,223,312 controls were included. Infection was not associated with an increased risk of epilepsy on a whole population level (HR 1.01, 95% CI 0.92-1.12). Statistically significant effects were observed in patients between 61 and 80 years (HR 1.66, 95% CI 1.37-2.02), also when adjusting for stroke, traumatic brain injury, tumours (same age group HR 1.50, 95% CI 1.24-1.82) and mechanical ventilation (HR 1.28, 95% CI 1.05-1.57). In patients 81-100 years, a similar significant difference was observed (HR 1.77, 95% CI 1.30-2.42), which remained after adjustment for stroke, traumatic brain injury and tumours (HR 1.51, 95% CI 1.10-2.05) but not when mechanical ventilation was included as a covariate (HR 1.34, 95% CI 0.97-1.84). Conclusions: On a whole population level, SARS-CoV-2 infections is not associated with an increased risk of epilepsy. In patients above 60 years, a moderately increased risk of epilepsy was observed. However, considering potential non-controllable bias and that Covid-19 patients in intensive care present with a lower risk than the general ICU population, the virus-induced epileptogenic effect is likely very small