Calcaneal bone mineral density in older patients who have fallen
From the 1Falls and Syncope Service, Royal Victoria Infirmary, Newcastle upon Tyne, 2School of Clinical Medical Sciences, University of Newcastle, and 3Musculoskeletal Unit, Freeman Hospital, Newcastle upon Tyne, UK
Address correspondence to Dr J.L. Newton, Care of the Elderly Offices, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP. email: julia.newton{at}nuth.northy.nhs.uk
Received 4 October 2005 and in revised form 31 January 2006
Background: Annually, 35–40% of those aged >65 years fall; up to 5% of such falls result in fracture. Fracture is determined both by propensity to fall and by bone fragility.
Aim: To determine osteoporosis prevalence and predictors in patients who have fallen.
Design: Observational cross-sectional study.
Methods: We measured calcaneal BMD in 408 consecutive patients aged >50 years attending after falling. Fall number, fracture history, weight, height, and risk factors for falls and osteoporosis were recorded. T scores (SD above or below the mean for young adults) were derived in both sexes, and Z scores (SD above or below age-related normal score) in females.
Results: In females (n = 300, 74%), mean (SD) T score was –1.1(1.6), and mean Z score was 0(1.4); 127 (42%) had osteoporosis (T score < – 1.6). ROC curves confirmed significant relationships between osteoporosis and age, weight and height (all p < 0.0001). Incorporating fracture history, our model (fracture aged >50 years, age >83 years, weight <57 kg, height <153 cm as dichotomous variables) predicted osteoporosis with 91% sensitivity, 34% specificity. Of 108 male fallers, 36 (33%) had osteoporosis. Age, height and weight all predicted osteoporosis (p < 0.02). The resulting model (fracture aged >50 years, age 
80 years, weight 
68 kg, height 167 cm as dichotomous variables) predicted osteoporosis with 92% sensitivity, 30% specificity.
Discussion: Osteoporosis prevalence is not increased in female fallers compared to age-related norms; empirical use of osteoporosis treatment solely on the basis of falls thus appears inappropriate. In both sexes, the factors predicting osteoporosis were age, height and weight. Where BMD is not practical, possible or economical, our model may be a sensitive means of predicting fallers with osteoporosis.