Mortality in myasthenia gravis: A nationwide population-based follow-up study in Denmark.
BACKGROUND
In previous studies of myasthenia gravis (MG), increased mortality has been reported. The aim of this study was to estimate mortality in patients with acetylcholine receptor antibody-positive (AChR-Ab-seropositive) MG in a nationwide population-based, long-term follow-up study.


METHODS
All AChR-Ab-seropositive MG patients, diagnosed between 1985 and 2005, were identified. Defined by age at diagnosis (≤ 50 or >50 years), patients were classified as having early- or late-onset MG. For comparison, 10 non-MG individuals from the general population were matched with each patient. All patients and controls were followed until January 1, 2009. Mortality rates and estimated mortality rate ratios (MRRs) were calculated.


RESULTS
Of 702 AChR-Ab-seropositive MG patients, 302 died during follow-up. Overall mortality was higher for patients with MG (MRR = 1.41, range 1.24-1.60). In late-onset women and men, the MRRs were 1.64 (1.36-1.99) and 1.22 (1.02-1.46), respectively. Total MRR was highest during the first 5 years after diagnosis.


CONCLUSIONS
MG diagnosis is still associated with increased mortality.
Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, byg 10, 8000, Aarhus C, Denmark.
Julie S
JS
Hansen
Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, byg 10, 8000, Aarhus C, Denmark.
Ditte H
DH
Danielsen
Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institute, Copenhagen, Denmark.
Finn E
FE
Somnier
Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
Trine
T
Frøslev
Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, byg 10, 8000, Aarhus C, Denmark.
Johannes
J
Jakobsen
Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
Søren P
SP
Johnsen
Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, byg 10, 8000, Aarhus C, Denmark.
Henning
H
Andersen
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood; D018672:Community Health Planning; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000453:epidemiology* / Q000401:mortality*; D016016:Proportional Hazards Models; D011950:Receptors, Cholinergic / Q000276:immunology; D012189:Retrospective Studies; D055815:Young Adult
D000906:Antibodies; D011950:Receptors, Cholinergic
Denmark; acetylcholine receptor antibody; mortality rate ratio; myasthenia gravis; seropositive myasthenia gravis