Vitamin D depletion in hip fracture women is associated with the occurrence of simultaneous upper limb fractures independently of bone mineral density
European Geriatric Medicine, Available online 31 October 2013
M. Di Monaco a, marco.di.monaco at alice.it; C. Castiglioni a; F. Vallero a; R. Di Monaco b; R. Tappero a
a Osteoporosis Research Center, and Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Strada Santa Margherita 136, 10131 Torino, Italy
b Department of Social Science, University Torino, via Sant’Ottavio 50, 10124 Torino, Italy
Introduction: Severe vitamin D deficiency is associated with the occurrence of simultaneous fractures at both hip and upper limb due to a single fall. We hypothesized that reduced bone mineral density (BMD) could explain the association.
Methods: We investigated 549 white women consecutively admitted to a rehabilitation hospital because of their first fall-related hip fracture. Thirty-three (6%) of the 549 women sustained a concomitant upper limb fracture of either distal radius (24 women) or proximal humerus (nine women). We assessed serum levels of 25-hydroxyvitamin D, hip BMD by dual-energy X-ray absorptiometry, and spine deformity index scores by lateral spine radiographs, 19.5 ± 7.1 (mean ± SD) days after fracture occurrence.
Results: Serum levels of 25-hydroxyvitamin D were significantly lower in the 33 women with concomitant fractures of both hip and upper limbs than in the remaining 516 (mean difference between groups 5.6 ng/ml, 95% CI from 3.5 to 7.6, P < 0.001).
Conversely, no significant differences were found in hip BMD or spine deformity index scores between the two groups. After adjustment for eight potential confounders, the occurrence of simultaneous fractures due to a single fall was significantly associated with low levels of 25-hydroxyvitaimn D (P = 0.001), but not with femoral BMD or spine deformity index scores.
Conclusion: The association between severe vitamin D deficit and the occurrence of concomitant fractures at both hip and upper limbs due to a single fall is independent of femur BMD. Further investigations should focus on altered fall pattern or reaction to fall.
The dependent variable was the presence of a concomitant fracture at the upper limb among the 549 women with a fall-related hip fracture. The independent variables were those listed in the Table. The presence of cognitive impairment, neurologic impairment, previous upper limb fractures, and fractures of the trochanteric region were conventionally attributed a value of one (the absence of these conditions and the presence of a cervical fracture were conventionally attributed a value of 0).