The incidence of SUDEP varies widely in different studies. A recent systematic meta-analysis reviewed studies reporting the incidence of SUDEP in different epilepsy populations. While the authors estimated incidence of SUDEP per 1000 person-years at 0.58 overall, 0.22 in childhood, and 1.2 in adulthood, they also found significant unexplained heterogeneity in studies reporting SUDEP incidence, suggesting the presence of unknown or unexplored risk factors.3 Despite the difficulties in objectively defining SUDEP incidence, the overall findings in studies follow typical neuroepidemiological trends, with lower incidence of SUDEP in primary care, population-based studies and higher SUDEP incidence in studies conducted in the tertiary care setting, theoretically reflecting the greater severity of epilepsy in referral centers. For example, in a population-based study of newly diagnosed epilepsy followed for the first 11 to 14 years after diagnosis, involving a cohort of 792 patients and 11,400 person-years, there were only 5 epilepsy-related deaths, one of which was due to SUDEP.4 Ficker et al5 retrospectively reviewed all deaths in patients diagnosed with epilepsy in Rochester, Minnesota, from 1935 to 1994, and compared findings with the expected rate of sudden death in the general population. They found SUDEP was a rare cause of death in the epilepsy population, with an incidence of 0.35 per 1000 person-years. This rate, however, was 24 times the expected sudden death rate in the general population. In contrast, results from studies in tertiary referral centers show higher rates of SUDEP. In a study evaluating sudden unexpected death in an adult outpatient cohort with epilepsy at a tertiary referral center, investigators reviewed records from 601 outpatients accounting for 1849 person-years, finding 11 unexpected deaths. The resultant incidence of SUDEP was 5.9 per 1000 person-years.6