Myasthenia gravis epidemiology in a national cohort; combining multiple disease registries
Article first published online: 4 MAR 2014
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Acta Neurologica Scandinavica
Special Issue: Selected Articles from the Annual Meeting of the Norwegian Neurological Association, Oslo, November 2013. This supplement was published with support from the Norwegian Neurological Society
Volume 129, Issue Supplement s198, pages 26–31, April 2014
How to Cite
Myasthenia gravis epidemiology in a national cohort; combining multiple disease registries. Acta Neurol Scand: 2014: 129 (Suppl. 198): 26–31. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd., , , .
- Issue published online: 4 MAR 2014
- Article first published online: 4 MAR 2014
- acetylcholine receptor antibody test;
- myasthenia gravis;
There is a wide variation in reported prevalence and incidence of myasthenia gravis (MG). In this study, we aimed to evaluate the validity of two nationwide databases by comparing prevalence and incidence rates reported from three recent studies using the two databases as case-finding method.
Materials and methods
Two different Norwegian nationwide databases were used: the acetylcholine receptor antibody database (reference cohort) and the Norwegian Prescription Database (NorPD) (study cohort). Presence of acetylcholine receptor antibodies (AChR) is specific for MG. Up to 85% of MG patients are AChR antibody-positive. All samples from the whole country were tested at one laboratory. NorPD contains patient information on all prescriptions of pyridostigmine.
Prevalence was 131 per million in the study cohort and 145 per million estimated from the reference cohort (Jan 1, 2008). No significant difference in prevalence between the study cohort and the reference cohort was found (SIR 1.1, 95% CI 1.0–1.2). The annual incidence rate was 16.0 per million in the study cohort and 8.8 per million estimated from the reference cohort, twofold more new MG patients were found in the study cohort compared to estimated figures from the reference cohort (SIR 1.8; 1.4–2.3).
This study confirms an optimal and unbiased case finding in both databases. Our calculated prevalence and incidence rates are in line with previous population-based studies. There was good agreement in prevalence reported from the two databases. The discrepancy in incidence is expected to diminish as years of study are increasing in NorPD.