Prevalence of epilepsy and the burden of underlying causes: Canadian validation of Danish estimates

Abstract Objective Recent work has provided population‐based estimates of the prevalence of cause‐specific epilepsy across the lifespan in Denmark. We sought to externally validate these Danish “secondary epilepsy” findings to ascertain consistency across geographic regions. Methods We conducted a population‐based cross‐sectional study using linked Alberta Health Care Insurance Plan administrative datasets. Epilepsy was identified using a validated algorithm. Point prevalence was calculated on December 31, 2018 among residents alive at that date. Secondary epilepsy was assigned when a recognized antecedent condition (stroke, traumatic brain injury [TBI], dementia, brain neoplasm, congenital brain malformations/perinatal conditions, or central nervous system infection) occurred before the first epilepsy diagnosis. If no antecedent condition was identified, the case was classified as “idiopathic.” In sensitivity analyses, Danish‐derived definitions were replaced with published validated case definitions. Results Among ~4.274 million Albertans, 26 056 prevalent epilepsy cases were identified (606 per 100 000; 584 females, 628 males). Idiopathic epilepsy accounted for 394 per 100 000 and secondary epilepsy for 212 per 100 000. Prevalence peaked in childhood, stabilized by early adulthood, and then increased after age 40 years, where male cases exceeded females. The proportional contribution of idiopathic epilepsy declined after midlife, with secondary epilepsy predominating by ages 65–70 years. Cause‐specific patterns were largely consistent with Denmark, exhibiting age‐dependency: congenital/perinatal causes in youth, TBI most common in young/middle‐aged adults, and stroke and dementia in older adults. Use of published validated definitions reduced secondary epilepsy prevalence to 139 per 100 000 and increased idiopathic prevalence to 467 per 100 000, largely driven by fewer cases attributed to stroke. Significance Secondary epilepsy becomes increasingly dominant with age, but cause‐specific attribution is sensitive to administrative case definitions. This highlights the need for rigorous and consistent algorithms to improve burden modeling, surveillance, and health‐system planning. These analyses validate the Danish estimates and inform future work deriving regional cause‐specific epilepsy burden.