Effect of oral vitamin D₂ yearly bolus on hip fracture risk in elderly women: a community primary prevention study

Abstract

Background and aims: Vitamin D deficiency is a well-known risk for hip fracture, and vitamin D insufficiency is so frequent in the elderly that population-wide preventive intervention would be useful. The objective of the study was to evaluate the efficacy of vitamin D bolus on hip fracture incidence in elderly women. Methods: All women aged >65 years registered at Health District 20 of the Regione Veneto, Italy, were eligible for this quasi-experimental, prospective community intervention study. A vial containing 400,000 IU vitamin D{in2} (Ostelin 800, Teofarma, Italy) was offered for oral administration to all women in the winters of 2000–2001 and 2001–2002. The only exclusion criteria for treatment were age and gender, and the control group included women who did not participate in the Health District initiative. Analysis of hip fracture incidence was carried out for 4 years, from 1999 to 2002. Patients with incident hip fracture were identified as soon as they were admitted to one of the 3 hospitals of the health district and interviewed regarding their participation in the vitamin D preventive intervention program. In 120 of the women (age range 68–90 years), serum concentrations of 25-OH vitamin D were measured from October to June, both before and 1 and 4 months after vitamin D administration. Results: 23,325 and 24,747 women received the vitamin D bolus during winters 2000–2001 and 2001–2002 respectively, i.e. 45–47% of eligible women. The proportion of women who accepted the bolus declined with advancing age, from 50–55% in women aged 60–70 years to 22–26% in those aged >90 years. The two-year intervention on the community decreased the incidence of fracture by 10% (p=0.050) in comparison with the previous two years. The age-adjusted risk reduction (RR) of hip fracture during 2001 and 2002 in women who had received vitamin D, with respect to women who had not, decreased by 17% (p=0.056) and 25% (p=0.005) respectively. The RR was considerably greater and statistically significant over both 2001 and 2002 in the cohort aged >75 years. 25-OH vitamin D concentrations, in the subset of women in whom it was measured, rose significantly (p<0.0001) by 9 ng/ml over 4 months after administration. Conclusion: Despite several obvious limitations due to its nature, this study sufficiently documents that yearly vitamin D bolus supplements, given as primary prevention to elderly Caucasian women, may decrease the incidence of hip fracture. For its probable safety and excellent feasibility and cost-effectiveness, this primary intervention has a great potential for generalisability.