Newly diagnosed single unprovoked seizures and epilepsy in Stockholm, Sweden: First report from the Stockholm Incidence Registry of Epilepsy (SIRE)

Summary Purpose: To describe and report initial findings of a system for prospective identification and follow-up of patients with newly diagnosed single unprovoked seizures and epilepsy in Stockholm, Sweden, the Stockholm Incidence Registry of Epilepsy (SIRE). Methods: From September 2001 through August 2004, a surveillance system has been in use to identify incident cases of first unprovoked seizures (neonatal seizures excluded) and epilepsy among residents of Northern Stockholm, an urban area with approximately 998,500 inhabitants. Potential cases are identified through multiple mechanisms: Network of health care professionals, medical record screening in specific hospital units, including outpatient clinics, emergency room services, and review of requests for electroencephalography (EEG) examination. Potential cases are classified 6 months after the index seizure based on review of medical records. Results: After screening approximately 10,500 EEG requests and 3,300 medical records, 1,015 persons met the criteria for newly diagnosed unprovoked seizures (430 single seizures; 585 epilepsy). The crude incidence for first unprovoked seizures and epilepsy was 33.9/100,000 person years, (the same adjusted to the European Standard Million), highest the first year of life (77.1/100,000) and in the elderly. No cause could be identified in 62.4%. Conclusions: We have established a sustainable system for prospective identification of new onset epilepsy cases in Stockholm. Despite a possible under-ascertainment, the registry provides a useful starting point for follow-up studies.