title: Complete ascertainment of Parkinson disease in the Swedish Twin Registry.
abstract: This report describes the ascertainment of Parkinson disease (PD) in all individuals aged 50 years or older (49,814 individuals) from the Swedish Twin Registry. In phase one of the study, all twins were screened for PD using telephone interviews, with a response rate of 72.7%. In phase two, twins with suspected PD were re-contacted to exclude anyone from follow-up who reported parkinsonian symptoms due to diseases other than PD. In the third phase, in-person clinical evaluations were completed for twins who were still considered PD suspects after phase two and for a sample of co-twins. During the clinical evaluations, we also collected blood samples and information about a variety of environmental exposures. Overall prevalence rate for PD was 496 per 100,000 individuals. Among the 132 PD cases identified, there were only three concordant twin pairs. In total 7.2% of PD cases reported a first degree relative with PD.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. karin.wirdefeldt@ki.se
authors.forename: Karin
authors.initials: K
authors.lastname: Wirdefeldt
authors.forename: Margaret
authors.initials: M
authors.lastname: Gatz
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Bakaysa
authors.forename: Amy
authors.initials: A
authors.lastname: Fiske
authors.forename: Måns
authors.initials: M
authors.lastname: Flensburg
authors.forename: Giselle M
authors.initials: GM
authors.lastname: Petzinger
authors.forename: Håkan
authors.initials: H
authors.lastname: Widner
authors.forename: Mark F
authors.initials: MF
authors.lastname: Lew
authors.forename: Mickie
authors.initials: M
authors.lastname: Welsh
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
mesh_terms: D004200:Diseases in Twins / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology*; D015995:Prevalence; D012042:Registries; D013548:Sweden / Q000453:epidemiology; D014427:Twins