title: Evaluation of a screening instrument for essential tremor.
abstract: To evaluate a screening instrument for essential tremor (ET) consisting of a seven-item questionnaire and a spiral drawing. A total of 2,448 Danish twins aged 70 years or more and a second sample aged 60 years or more (n = 1,684) from a population-based northern German cross-sectional study (PopGen ET) were screened for ET. Inclusion criteria were a previous diagnosis of ET, a positive answer to two or more questions of the questionnaire or a spiral rating >4 (range of scale 0-9). Three hundred thirteen of 380 positively screened and 321 negatively screened subjects were clinically examined. Definite or probable ET was diagnosed in 104 patients, possible in 86 and other tremors in 98 patients. The sensitivity of the screening instrument was 70.5%, the positive predictive value was 64.9%, the specificity was 68.2%, and the negative predictive value was 73.5%. Tremor severity correlated significantly with higher spiral scores and more positive items. More patients were identified by spiral drawing in all tremor groups. The interrater and intrarater reliability for spirals ranged from 0.7 to 0.8 using intraclass coefficient. A cluster analysis revealed that the questionnaire can be reduced to three items, about uncontrollable tremor in any body part, tremor while drinking or pouring and other family members with tremor, without loosing efficacy. We present an easy to use and reliable screening instrument that is effective to identify patients with ET but not able to exclude patients with other tremor forms.
authors.affiliation: Department of Neurology, Christian-Albrechts-University Kiel, Germany.
authors.forename: Delia
authors.initials: D
authors.lastname: Lorenz
authors.affiliation: Department of Neurology, Christian-Albrechts-University Kiel, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Papengut
authors.affiliation: The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Frederiksen
authors.affiliation: Department of Neurology, Christian-Albrechts-University Kiel, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Kopper
authors.affiliation: Department of Neurology, Christian-Albrechts-University Kiel, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Klebe
authors.affiliation: The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
authors.affiliation: Institute of Clinical Molecular Biology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schreiber
authors.affiliation: Department of Neurology, Christian-Albrechts-University Kiel, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Deuschl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D020329:Essential Tremor / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods; D014427:Twins / Q000235:genetics*