OBJECTIVE: To determine the risk of osteoporosis in patients with myasthenia 
gravis (MG) in a large cohort representing 99% of the population of Taiwan.
METHODS: Data from the Taiwan National Health Insurance Research Database were 
used to conduct retrospective cohort analyses. The study cohort consisted of 
2,073 patients with MG who were 3-fold frequency-matched by age and sex and 
assigned the same index year as a comparison cohort without MG. Cox proportional 
hazard regression analysis was conducted to estimate the risk of osteoporosis.
RESULTS: The MG cohort had a 1.96-fold increased risk of developing osteoporosis 
compared with the comparison cohort (hazard ratio [HR] = 1.96, 95% confidence 
interval [CI] = 1.57-2.44). Patients with MG older than 30 years developed an 
increased risk of osteoporosis, with the highest risk in the age group from 30 
to 44 years, compared with the control cohort. Corticosteroid-naïve patients 
with MG had a 1.52-fold increased risk of developing osteoporosis (HR = 1.52, 
95% CI = 1.11-2.08), and the corticosteroid-treated cohort had a 2.37-fold 
increased risk of developing osteoporosis (HR = 2.37, 95% CI = 1.82-3.07).
CONCLUSION: This population-based retrospective cohort study provides evidence 
that MG is associated with a high risk of osteoporosis regardless of 
corticosteroid use.