Low Serum Vitamin D Levels Associated With Higher Mortality in Elderly Men: Presented at ASBMR

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Title: Low Serum Vitamin D Levels Associated With Higher Mortality in Elderly Men: Presented at ASBMR
URL: http://www.pslgroup.com/dg/22C612.htm
Doctor's Guide
September 15, 2008

By Danny Kucharsky

MONTREAL -- September 15, 2008 -- Low serum vitamin D levels in older men are associated with a higher risk of cardiovascular mortality, noncancer mortality, and noncancer, noncardiovascular mortality, according to research presented here at the American Society for Bone and Mineral Research (ASBMR) 30th Annual Meeting.

Although low 25-hydroxy vitamin D (25-OH vitamin D) levels have previously been associated with an increased risk of fractures and some diseases in older men, few studies of all-cause and cause-specific mortality have previously been conducted in elderly males, said Peggy Cawthon, California Pacific Medical Center Research Institute, San Francisco, California, who presented results from the prospective study here on September 12.

"There's been a lot of interest in vitamin D levels and various health conditions in older adults, and some recent observational studies have suggested there is an association between higher vitamin D and protection for mortality, so the more vitamin D you have, the less likely you are to die," Cawthon explained.

To test the hypothesis that low serum levels of vitamin D are associated with an increased risk of mortality in older men, the researchers looked at 5,995 men aged 65 years and up at 6 clinics in the United States. All subjects were participating in the Osteoporosis Fractures in Men study. An analysis sample of 1,608 men was randomly selected, and the subjects were followed for 6.1 years.

Proportional hazards models were used to test associations between low vitamin D levels and overall mortality, noncancer mortality, and cancer mortality as well as cardiovascular death. Adjustments were made for factors such as age, clinical centre, and season of the blood draw.

The study found that men with vitamin D deficiency (≤15 ng/mL) had a 2.2-fold increased risk of death due to causes besides cancer, with no significantly increased mortality for those with levels of 15 to 30 ng/mL (P = .008).

The researchers also found, however, that there was no significant association between 25-OH vitamin D deficiency and death due to all types of cancer combined (relative hazard = 0.6; confidence interval, 0.2-1.4), with results for vitamin D deficiency similar to results in the lowest quartile of 25-OH vitamin D levels (≤20 ng/mL) compared to those in men in the highest quartile (≥30 ng/mL) (P = .12).

"We saw the opposite of what we expected," Cawthon noted. "There's not any other information in the literature that would suggest that association, and we're not really sure why that is."

Potential harmful effects of higher vitamin D levels should be investigated further in larger studies with better power, the investigators concluded. "We'd like to look at this in [the setting of] a randomised, controlled trial," Cawthon said.

[Presentation title: Low Vitamin D Levels and Risk of Death in Older Men: A Prospective Study. Abstract F335]

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