Mortality in myasthenia gravis: A nationwide population-based follow-up study in Denmark.

INTRODUCTION

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.