Relatively little is Asian men and african about the bone health of ethnic groups within the UK and data are largely restricted to women. The aim of this study was to investigate ethnic differences in areal bone mineral density Asian men and africanvolumetric bone mineral density vBMDbone geometry and strength in UK men.
Adjustments were made for age, weight and height. Black men had higher aBMD at the whole body, total hip and femoral neck compared to White and South Asian men independent of body size adjustments, with no differences between the latter two groups. White men had longer hip axis lengths than both Black and South Asian men. At the tibia and radius diaphysis, Black men had larger bones with thicker cortices and greater bending strength than the other groups.
There were fewer differences between White and South Asian men. At the diaphysis, after size-correction, South Asian men had similar sized bones but thinner cortices than White men; measures of strength were not broadly reduced in the South Asian men. Combining pQCT and DXA measurements has given insight into differences in bone phenotype in men from different ethnic backgrounds. Understanding such differences is important in understanding the aetiology of male osteoporosis. Osteoporosis is an important health problem through its association with age-related fractures and consequent morbidity and mortality.
There are important differences in the occurrence of age related fractures between different regions and populations, which are likely due to variation in bone strength and, or trauma — particularly fall risk. However, there are few data concerning bone mass and strength, and the underlying determinants of fracture Asian men and african in UK ethnic minority groups, with no data in men.
Conversely South Asian women were reported to have a lower lumbar spine and femoral Asian men and african aBMD compared to White European women, however, after correcting for skeletal size the differences at the lumbar spine were attenuated .
These studies illustrate the limitations of DXA when describing population differences  where body size and habitus differ.
Using peripheral quantitative computed tomography pQCT has advantages because it measures volumetric BMD vBMDcortical and trabecular compartments separately and provides information also about other structural parameters which contribute to bone strength. There are limited data comparing Asian men and african measurements in different ethnic groups. Thus, it is possible that bones of pre-menopausal South Asian women may be efficiently adapted to a lower BMC as a result of a different distribution of bone mineral within the periosteal envelope, thereby preserving bone strength .
Whether these findings are similar in men remains unknown. We investigated also whether any observed differences could be explained by body weight and height.
The men subsequently attended a follow-up assessment of identical measurements a median Asian men and african 4. The results reported here are from the follow-up assessment. Ethnicity was defined by participants' self-report with 3 of 4 grandparents being of identical Asian men and african origin. Recruitment for these ethnic groups was through a combination of approaches including advertising in community centers and through local media targeted at the relevant ethnic groups.
At their clinic visit, participants completed an interviewer-assisted questionnaire which included questions to determine their Physical Activity in the Elderly PASE score . Smoking status was assessed by asking whether participants had ever smoked at least cigarettes or been a regular pipe or cigar smoker. Those answering yes to any of the questions were considered as ever smokers. Ethical approval for the study was obtained in accordance with the local ethics review board in Manchester.
All participants provided written informed consent. Body mass index BMI was calculated as weight in kilograms kg divided by the square of height m.
Measurements of aBMD at the whole body, total hip, femoral neck and lumbar spine L1—4 were obtained; the non-dominant proximal femur was scanned. Hip axis length HALwhole body fat mass and lean mass were Asian men and african measured. All scans were reported by an experienced musculoskeletal Asian men and african JEA.
Standard manufacturer QA and QC procedures were followed using manufacturer Hologic provided phantoms. All measurements were made in the non-dominant limb.
Forearm length was defined as the distance from the styloid process of the ulna to the olecranon. Leg length was defined as the distance from the most proximal edge of the medial malleolus to the intercondylar eminence. The scan sites were determined using a planar scout view of the distal radius or tibia and the reference line was placed to bisect the lateral border of the endplate.
Medullary area mm 2was calculated by total area minus cortical area. CSMI and SSI are measures of bending and torsional strength at the diaphysis and have been related to fracture load .
Where significant motion artefact was detected, scans were excluded.
Manufacturer's standard QA and QC procedures were Asian men and african using manufacturer supplied phantoms. Differences in descriptive characteristics were assessed using one-way analysis of variance with a Bonferroni multiple-comparison test.
Differences in smoking status were assessed using a chi squared test. To investigate the ethnic differences in DXA and pQCT parameters, we performed linear regression analyses, with bone parameters as the dependent variable and ethnicity as the independent variable, with adjustments made for age, weight and height. We used the fitted regression lines to perform Asian men and african comparisons between ethnic groups, correcting for multiple comparisons using the Bonferroni method.
All analyses were performed in Stata, Version Three hundred and forty three participants were included in the analyses, White, 44 Black and 64 South Asian men. White men were older than the Black and South Asian men. South Asian men were shorter than White men Compared to Black and White men, total lean mass was lower in South Asian men, with no significant difference in total fat mass between groups. Whole body fat mass to lean mass ratio was higher in South Asian men compared to White and Black men.
The percentage of subjects who were ever smokers was lower in South Asian compared to White men. Black men had higher aBMD at the whole body, total hip and femoral neck than White men.
These differences persisted after adjustment for Asian men and african, weight and height Table 2.
There were no significant differences in cortical Asian men and african trabecular vBMD at the radius following adjustments Table 3. At the diaphysis of the radius, Black men had thicker cortices and greater cortical area. There were no Asian men and african differences in aBMD between White and South Asians except at the whole body; this difference was attenuated and became nonsignificant after adjustment for age, height and weight Table 2.
South Asians had smaller CSA at the metaphysis and diaphysis of the radius, following adjustment, differences at the diaphysis were attenuated Table 3. South Asians had smaller cortical area and consequently thinner cortices at the diaphysis of the radius and tibia, however, CSA and CSMI were similar to White men at both sites following adjustments; SSI was lower in South Asian men at the tibia yet similar at the radius compared to White men Table 3Table 4.
South Asian men had lower aBMD at the whole body, total hip, femoral neck and lumbar spine; the difference at the lumbar spine was attenuated following adjustments Table 2. In this study, for the first time, we describe the ethnic differences in BMD, bone geometry and bone bending and torsional strength in UK men. Black men had higher aBMD compared to White and South Asian men, and these differences were independent of weight and height, in contrast differences in aBMD between White and South Asian men were attenuated by correcting for body size.
Rather, the geometry of bone differed between the groups and mostly at the diaphyseal sites, and hip axis length was longer in White men. At the radius and tibia diaphysis, Black men had more cortical bone within a slightly larger periosteal envelope and consequently greater bending strength than the other two groups. For Asian men and african same size and body weight, South Asian men had similar sized bones compared to White and Black men at the diaphysis but had thinner cortices.