title: Clinical and laboratory-reconfirmed myasthenia gravis: a population-based study.
abstract: The aim of this study was to compare the clinically based prevalence of myasthenia gravis (MG) with the prevalence of laboratory-confirmed cases. All patients with a diagnosis of MG living in Estonia as on 1 January 1997 were asked to participate in re-examination. The criteria for laboratory-supported MG were weakness and rapid fatigue and a positive outcome of at least one of three laboratory tests: (i) blinded acetylcholinesterase inhibitor test; (ii) determination of antibodies to acetylcholine receptor and (iii) neurophysiological examination using repetitive nerve stimulation and single-fibre EMG. Eighty-nine patients were re-examined and 70 patients (79%) fulfilled the criteria of laboratory-supported MG. The corrected prevalence ratio was 78 per million. In the non-confirmed MG group, there was more women (92%) than men (43%) whose diagnosis was established within 1 year from onset of symptoms (P = 0.016). In all women with non-confirmed MG the diagnosis was established within 1 year from referral to the physician, whereas 68% of women with confirmed MG was diagnosed within 1 year (P < 0.0001). Thus, we conclude that, in Estonia the prevalence of MG based on medical records seems overestimated by 21% and women are at higher risk of obtaining an uncertain diagnosis of MG.
authors.affiliation: Department of Neurology, Tartu University Hospital, Tartu, Estonia. merle@akhphd.au.dk
authors.forename: M
authors.initials: M
authors.lastname: Oöpik
authors.forename: L
authors.initials: L
authors.lastname: Puksa
authors.forename: S-M
authors.initials: SM
authors.lastname: Lüüs
authors.forename: A-E
authors.initials: AE
authors.lastname: Kaasik
authors.forename: J
authors.initials: J
authors.lastname: Jakobsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002800:Cholinesterase Inhibitors; D018672:Community Health Planning; D004576:Electromyography; D004957:Estonia / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D009482:Neurophysiology / Q000379:methods; D015995:Prevalence; D011950:Receptors, Cholinergic / Q000276:immunology; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D002800:Cholinesterase Inhibitors; D011950:Receptors, Cholinergic