Vitamin D insufficiency: a risk factor to vertebral fractures in community-dwelling elderly women

Abstract

Objective: To determine the risk factors for the presence of moderate/severe vertebral fracture, specifically 25-hydroxyvitamin D (25-OHD).

Study design: Cross-sectional study conducted for 2 years in the city of São Paulo, Brazil including community-dwelling elderly women.

Methods: Bone mineral density (BMD), serum 25-OHD, intact parathyroid hormone (iPTH), calcium and estimated glomerular filtration rate (eGFR) were examined in 226 women without vertebral fractures (NO FRACTURE group) and 189 women with at least one moderate/severe vertebral fracture (FRACTURE group). Vertebral fracture assessment (VFA) was evaluated using both the Genant semiquantitative (SQ) approach and morphometry.

Results: Patients in the NO FRACTURE group had lower age, increased height, higher calcium intake, and higher BMD compared to those patients in the FRACTURE group (p<0.05). Of interest, serum levels of 25-OHD in the NO FRACTURE group were higher than those observed in the FRACTURE group (51.73 nmol/L vs. 42.31 nmol/L, p<0.001). Reinforcing this finding, vitamin D insufficiency (25-OHD<75 nmol/L) was observed less in the NO FRACTURE group (82.3% vs. 93.65%, p=0.001). After adjustment for significant variables within the patient population (age, height, race, calcium intake, 25-OHD, eGFR and sites BMD), the logistic-regression analyses revealed that age (OR=1.09, 95% CI 1.04-1.14, p<0.001) femoral neck BMD (OR=0.7, 95% CI 0.6-0.82, p<0.001) and 25-OHD <75 nmol/L (OR=2.38, 95% CI 1.17-4.8, p=0.016) remains a significant factor for vertebral fracture.

Conclusion: Vitamin D insufficiency is a contributing factor for moderate/severe vertebral fractures. This result emphasizes the importance of including this modifiable risk factor in the evaluation of elderly women.