Prevalence of vitamin D inadequacy in osteoporotic hip fracture patients in London.

BACKGROUND

It is well established that vitamin D levels are suboptimal in the elderly and that adults with fragility fracture are more likely to have serum vitamin D levels either lower than those of control patients of similar age, or below the normal range.

OBJECTIVES

To investigate the prevalence of vitamin D inadequacy in an elderly population with hip fractures from London (UK) and compare levels with data previously presented from Glasgow (UK).

RESEARCH DESIGN AND METHODS

A retrospective patient audit was carried out over a 17-month period (September 2003-January 2005). Patient records were searched for hip fracture admissions and cross matched with vitamin D analysis carried out within 3 days of the hip fracture admission. The resulting records were hand searched to exclude patients with a hip fracture resulting from high impact/trauma.

RESULTS

There were data for 103 hip fracture patients, 79.6% of the patients were women (n = 82). The mean age at the time of fracture was 73.4 years, 100% were aged 60 years or over and 41% were aged 75 years or over. Around 20% of the patients were receiving supplementation with calcium and/or vitamin D and were not excluded from the analysis. The mean vitamin D level was 32.1 nmol/L (12.9 ng/mL), SD = 19.4 (7.8), however, it is likely that the true mean is lower since in approximately 15% of cases vitamin D levels were reported as < 12.5 nmol/L, but were transcribed at 12.5 nmol/L in order to allow a numerical value to be calculated. Ninety-nine per cent of patients had a vitamin D level < 80 nmol/L, 94.2% < 70 nmol/L and 81.6% < 50 nmol/L. There were no significant differences by patient age or sex, however, there were significant seasonal differences in vitamin D. In the year from September 2003 to August 2004, 82.8% of summer admissions had vitamin D levels < 70 nmol/L compared with 98.0% in winter (p = 0.04). Mean vitamin D levels in the 30 patients with parathyroid hormone (PTH) levels above the reference range were significantly lower than levels in the 71 patients within the range: mean 19.9 nmol/L, SD = 16.2 versus mean 37.5 nmol/L, SD = 18.5 (p < 0.0001). Furthermore, 50% of the patients with PTH levels above the reference range had vitamin D levels < 12.5 nmol/L, reflecting extremely low levels of vitamin D.

CONCLUSIONS

This study confirms almost universal vitamin D inadequacy among 103 patients admitted to hospital with hip fracture in London, although the prevalence of inadequacy is slightly lower than that seen in a similar study carried out in Glasgow.