Introduction: While multiple sclerosis (MS) is usually diagnosed in young adults, many individuals living with the diagnosis are above age 40 years. Osteoporosis and fractures, which are morbidities generally associated with ageing but also physical inactivity, were determined in patients before and after MS diagnosis and compared with a matched MS-free population.

Methods: Incident MS patients diagnosed in 2008-2016 were identified in the Swedish National Patient Register and matched with 10 MS-free individuals by age, sex, and region of residence. Incidence rates (IR) per 10,000 person-years and incidence rate ratios (IRRs; vs the MS-free cohort) of osteoporosis and fractures by sex and age at event were calculated after MS diagnosis based on ICD-10 codes from inpatient and outpatient specialist care.

Results: In total, 6,602 MS patients were identified and compared with 61,828 without MS (female, 69%; median age, 40 years). Before MS diagnosis, MS patients showed significantly increased proportions of osteoporosis (0.5% vs 0.3%) and fractures (12.6% vs 11.4%) compared with the MS-free cohort.After diagnosis, MS patients had an increased risk of osteoporosis (IRR 1.69; 95% confidence interval [CI] 1.22-2.35). The increased risk of osteoporosis among MS patients was observed for both sexes (females, IRR 1.60; 95% CI 1.13-2.28 and males, IRR 2.56; 95% CI 1.04-6.31), as well as in the older age strata 40-59 years (IRR 2.39; 95% CI 1.47-3.89) and ⩾60 years (IRR 1.69; 95% CI 1.06-2.70), but not among those aged < 40 years. Similarly, an increased risk of fractures among MS patients (IRR 1.37; 95% CI 1.24-1.51) was shown for both females (IRR 1.40; 95% CI 1.25-1.58) and males (IRR 1.29; 95% CI 1.07-1.55), as well as the age strata 40-59 years (IRR 1.52; 95% CI 1.31-1.76) and ⩾60 years (IRR 1.92; 95% CI 1.58-2.33), but not those aged < 40 years.

Conclusions: The risk of osteoporosis and fractures was moderately increased in MS patients of both sexes and in the older age groups, which may relate to physical inactivity and an increased risk of falls.