Incidence of fractures in patients with multiple sclerosis: the Danish National Health Registers

Background: Patients with multiple sclerosis (MS) are potentially at high risk of fracture due to falls and osteoporosis. Objective: To estimate incidence rates of fractures in MS patients, stratified by fracture type, sex and age, and to compare these rates with controls. Methods: The case population consisted of all patients with an accepted diagnosis of MS in the Danish MS Registry (1949-2007). Data were linked to the National Hospital Discharge Register (1977-2007). Patients with MS (n = 11,157) were 1: 6 matched by year of birth, gender, calendar time and region to persons without MS (controls). Incidence rates of fracture were estimated as the number of fractures per 1000 person-years. Incidence rate ratios (IRRs) were calculated by dividing fracture rates in MS patients by fracture rates in controls. Results: Among patients with MS, the incidence rate of any fracture yielded 22.8 per 1000 person-years. The IRR of any fracture between MS patients and controls was 1.40 (95% CI 1.33-1.46). In particular, IRRs of tibia fracture (3.36 [2.75-4.11]), femur fracture (6.66 [5.06-8.76]) and hip fracture (3.20 [2.83-3.62]) were elevated in MS patients versus controls. Conclusion: Fractures occurred more often in patients with MS, especially fractures of the tibia, hip and femur.