Ten-year fracture risk in Japanese patients with myasthenia gravis: A comprehensive assessment using the fracture risk assessment tool.

BACKGROUND: Myasthenia gravis (MG) is an immune disorder that causes muscle weakness with an increasing prevalence, particularly among the elderly in Japan. Glucocorticoid treatment for MG is problematic for bone health because of reduced bone density and increased fracture risk. The fracture risk assessment tool (FRAX®) can estimate fracture risk, but its applicability in patients with MG remains uncertain.

METHODS: A prospective cohort study was conducted on 54 patients with MG between April and July 2012. Bone mineral density (BMD) was measured, and FRAX® scores were calculated with and without BMD. We also adjusted FRAX® scores based on glucocorticoid dosage. Patients were monitored for major osteoporotic fractures (MOF) until June 2022. Statistical analyses included Kaplan-Meier curves and Cox proportional hazards models.

RESULTS: The study group included 12 men and 42 women with a mean age of 62 years. Higher FRAX® scores correlated with increased fracture risk, particularly in the hip and lumbar regions. The 10-year fracture-free rate was significantly lower in the high-FRAX® score group. The FRAX® score using BMD is a significant predictor of MOF risk. The hazard ratio for FRAX® scores was 1.17 (95% CI 1.10-1.26).

CONCLUSION: We demonstrated the effectiveness of the FRAX® tool in assessing fracture risk among patients with MG. High FRAX® scores correlated with increased fracture risk, emphasizing its importance. These findings support the incorporation of FRAX® assessment into clinical management to enhance patient care and outcomes. However, the small sample size and observational nature suggest a need for further research.