Q J Med 2004; 97: 95-99
© Association of Physicians 2004; all rights reserved.
Bone mineral status in immigrant Indo-Asian women
From the 1Department of Rheumatology, Charing Cross Hospital, London, 2Osteoporosis Centre, 3Engineering Section, Department of Medical Physics and Bioengineering, and 4MRC Environmental Epidemiology Unit, Southampton General Hospital, Southampton, and 5Brighton and Sussex Medical School, University of Sussex, Brighton, UK
Received 14 October 2003 and in revised form 1 December 2003
Background: Indo-Asian immigrants are known to be at high risk of metabolic bone disease, but the prevalence of osteoporosis in this population is unknown.
Aim: To compare the bone mineral at the lumbar spine and femoral neck of Indo-Asian immigrant women with that of age-matched Caucasian women.
Design: Retrospective analysis.
Methods: Women of Indo-Asian origin referred for bone density scans in the last five years were identified. The skeletal status of each was compared with an age-matched Caucasian control for bone mineral content (BMC), bone mineral density (BMD) and bone mineral apparent density (BMAD) at the lumbar spine and femoral neck, and hip axis length was measured.
Results: At the lumbar spine, Indo-Asians had a significantly lower BMD than Caucasians (0.834 vs. 0.913, p = 0.008), but there was no significant difference when BMAD values were calculated (0.123 vs. 0.122). At the femoral neck, there was no difference in BMD (0.728 vs. 0.712, p = 0.5), and BMAD values were significantly higher among Indo-Asians than Caucasians (0.393 vs. 0.319, p = 0.022). Hip axis length was significantly shorter among Indo-Asian women (10.3 vs. 10.7, p = 0.009).
Discussion: Although Indo-Asian women appear to have lower spinal BMD than Caucasians, these differences disappear when BMAD values are calculated. While BMD is an areal density, not taking into account the ‘depth’ of the bone, BMAD is an estimation of volumetric density. Hence lower BMD values in Asians may be a size-related artefact. Longitudinal studies may be required to evaluate the use of BMD as a marker for fracture risk in this population.
Address correspondence to Dr K. Walker-Bone, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton BN1 9PX. e-mail: k.walker-bone{at}bsms.ac.uk