Objectives: We have previously shown that MS patients have significantly reduced bone mass and a high prevalence of abnormal vitamin D status. The object of this study was to characterize the frequency of adulthood fractures in MS patients, prospectively determine rates of bone loss in MS, and determine whether vitamin D status is a predictor of bone loss.
Methods: MS patients (36 women, 18 men) were compared with age- and gender-matched healthy controls (35 women, 14 men). Bone mass was performed by dual x-ray absorptiometry at baseline and at 12-month intervals over 2 years.
Results: Fractures in the absence of major trauma had occurred in 2% of controls and 22% of MS patients (p < 0.002). Over the 2 years of prospective follow-up, both women and men with MS lost substantially more bone in the femoral neck than did controls (3% and 6% per year in pre- and postmenopausal women with MS versus 0.5% and 0.8% per year in controls; 7.3% per year in men with MS versus 1.6% per year in controls). Bone loss in the spine was also greater in women with MS than in controls (1.6 to 3.5% per year loss in MS patients versus no change in controls). Duration of steroid treatment beyond 5 months and ambulatory status were both predictors of bone loss. Bone loss in the spine occurred faster in MS patients with low (<20 ng/mL) 25-hydroxyvitamin D levels (1.9% per year, p < 0.04), whereas in those with normal 25-hydroxyvitamin D levels, bone loss was insignificant. At the femoral neck, bone loss was substantial in all patients, but was somewhat faster in the group with low levels of 25-hydroxyvitamin D (5.6% per year, p < 0.0001) compared with the group with high levels of 25-hydroxyvitamin D (4.3% per year, p = 0.03).
Conclusions: MS patients have more frequent fractures and lose bone mass more rapidly than do their healthy age- and gender-matched peers, in part related to insufficient vitamin D. Vitamin D repletion in MS patients who are deficient might reduce, to some extent, the rate of bone loss and decrease osteoporosis-related fractures.