Quantitative ultrasound of the calcaneus and falls risk in the institutionalized elderly: sex differences and relationship to vitamin D status.

Very frail older people constitute an increasing proportion of aging populations and are likely to contribute substantially to costs due to osteoporosis. Quantitative ultrasound (QUS) of the calcaneus is potentially a simple method for assessing fracture risk in frail elderly, but there have been few studies of male/female differences in QUS or its relationship to falls risk or vitamin D status, which is often subnormal in this population. We studied QUS, falls risk and serum 25(OH)-vitamin D in subjects living in institutional aged care facilities (hostels or nursing homes). The study sample comprised 294 men (mean age 81.2 years, range 65-102 years) and 899 women (mean age 86.7 years, range 65-104 years). Broadband ultrasound attenuation (BUA) and velocity of sound (VOS) were higher in men than women by approximately 30% and 2% respectively ( p<0.0001) and this difference was maintained at all ages. Serum 25(OH)D levels were higher in men than women ( p<0.001) but vitamin D deficiency was very common in both sexes and serum 25(OH)D was not associated with QUS in either sex. There was no significant decline in BUA or VOS with age in men; however, for women BUA declined by 2.8-4.7% per decade and VOS by 1% per decade (both p<0.001). Mean BUA T-scores were -1.55 and -2.48 at age 90 years in men and women. Quadriceps strength and weight but not serum 25(OH)D were significantly associated with BUA. These data suggest only minor loss occurs at the calcaneal site in BUA and VOS with very old age in either sex.