Bone mineral density in ethnic Norwegians and Pakistani immigrants living in Oslo--The Oslo Health Study

Hip geometry in hip fracture patients in Greenland occurring over a 7.7-year period

Background

Hip geometry influences hip fracture risk. Hip fractures are common, and they are associated with pain, disability, premature death and marked costs on society. Osteoporotic fractures are frequent in Arctic populations and increase with advancing age in this society with a steep rise in life expectancy. Greenland Inuit is a distinct ethnic group, and data on hip geometry is missing. We thus aimed to describe hip geometry in 7.7 years of consecutive hip fracture patients in Greenland.

Methods

We evaluated collodiaphysial angle, femoral neck length, the outer and inner diameter of the femur at 2 and 5 centimetres below the centre of the lesser trochanter and the cortical thickness from pelvic and hip radiographs in all patients operated in Greenland over 7.7 years. We included all 84 patients with one non-fractured hip visible for geometric analysis. Analyses were conducted in duplicate.

Results

We found a collodiaphysial angle of 134.8/132.6^o in men/women (p = 0.06) and a femoral neck length of 38.0/33.9 mm in men/women (p = 0.001). Cortical thickness was affected by sex in the adjusted analysis (p < 0.001). Cortical thickness index at 5 cm below the centre of the lesser trochanter decreased with age (p = 0.026) and may be influenced by height (2 cm below the centre of the lesser trochanter, p = 0.053).

Conclusion

Our findings differed from European data and suggest a delicate balance in hip geometry in Arctic populations. Ethnic peculiarities influence the structure of the hip and may influence fracture risk. A focus on hip geometry and risk factors for osteoporotic fractures in Arctic populations is warranted.

Ethnic differences in risk of hip fracture in Norway: a NOREPOS study

Hip fracture is a major public health problem, and the incidence rates vary considerably between countries. Ethnic differences in bone mineral density have been identified as a factor to explain some of the geographical differences in rates of hip fracture. In this Norwegian register-based study, we found that all immigrant groups experienced lower risk of hip fracture than individuals born in Norway.

INTRODUCTION

Norway is among the countries with the highest incidence rates. The aim of this study was to investigate differences in risk of hip fracture between ethnic groups living in Norway.

METHODS

We linked individuals in the Norwegian Population and Housing Census conducted in 2001 and a database consisting of all hip fractures in Norway in the period 2001-2013. Residents (n = 1,392,949) between 50 and 89 years and born in nine different geographical regions of the world were examined, and we computed age-standardized incidence rates for the different geographic regions-denoted ethnic groups in the paper. Gender-stratified Cox regression analysis, adjusted for age, was used to model risk of hip fracture as a function of region of birth.

RESULTS

Age-standardized incidence rates of hip fracture varied considerably between regions of birth living in Norway, in both genders. All immigrant groups had lower risk of hip fracture compared to the Norwegian-born population. Immigrants from Central and Southeast Asia had the lowest risk of hip fracture when compared to individuals born in Norway (HR = 0.2, 95% CI 0.1-0.3 and HR =0.2, 95% CI 0.2-0.4 in men and women, respectively).

CONCLUSION

Lower risk of hip fracture was found in all immigrant groups compared to the Norwegian-born majority population.

Vitamin D status in patients attending a Danish migrant health clinic: a clinical retrospective study

Non-western migrants and ethnic minority populations in western countries are particularly at risk of vitamin D deficiency due to darker skin color and low sun exposure. The aim of this study was to examine levels of 25-OH vitamin D in patients attending a Danish health clinic for migrants. Patients attending the clinic represent a distinct group of migrants with longstanding, unresolved symptoms and often multiple illnesses. In this retrospective study, data on patient demographics and vitamin D levels were extracted from the medical records of 156 patients attending a Migrant Health Clinic in 2008-2011 who were considered at-risk for low vitamin D, mainly due to symptoms of diffuse pain in the muscles, bones or joints. Over the follow-up period of 1 year, the number of patients with vitamin D below 50 nmol/L decreased from 80 to 56%. The median vitamin D level increased from 27 nmol/L [(interquartile ranges (IQR 14.5-45.0)] at baseline to 45 nmol/L (IQR 26.5-64.5) at follow-up. Patient consultations with a holistic approach and close follow-up can help patients with complex symptoms and language barriers to overcome barriers to treatment and adherence, thus leading to improved levels of vitamin D.

Ethnic differences in bone geometry between White, Black and South Asian men in the UK

Relatively little is known 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 (aBMD), volumetric bone mineral density (vBMD), bone geometry and strength in UK men. White European, Black Afro-Caribbean and South Asian men aged over 40years were recruited from Greater Manchester, UK. aBMD at the spine, hip, femoral neck and whole body were measured by DXA. Bone geometry, strength and vBMD were measured at the radius and tibia using pQCT at the metaphysis (4%) and diaphysis (50% radius; 38% tibia) sites. 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. There were fewer differences in vBMD but White men had significantly lower cortical vBMD at the tibial diaphysis than Black and South Asian men (p<0.001). 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 metaphysis, South Asian men had smaller bones (p=0.02) and lower trabecular vBMD at the tibia (p=0.003). 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.

La Compleja Relación Entre Posición Socioeconómica, Estatus Migratorio y Resultados de Salud

INTRODUCTION

The relationship between socioeconomic position (SEP), migration and health is dynamic, difficult to predict, multifactorial and poorly studied in the Latin American region. Moreover, there are high levels of uncertainty about reasons, types, and consequences of migration to an individual, family, community, country of origin and the receiving country.

OBJECTIVE

To discuss the evidence about the complex relationship between SEP, migration and health outcomes.

RESULTS

According to international evidence available, migration has a direct impact on health outcomes in a population and, in turn, on public health policy decisions in each locality. The available evidence on this issue affects multiple parts of the social sciences. The "healthy migrant" effect is not consistently observed among immigrant populations, particularly after adjusting for PSE. Moreover, the immigrant population tends to assimilate in terms of risk factors and morbidity to the local population after about 10 years of stay in the foreign country. Migration has consequences for international relations, economic productive capacity of a country, inequality, demographic changes and health outcomes, to mention a few.

CONCLUSION

There is now the opportunity to generate better and more evidence longitudinal population-based around the relationship between SEP, migration status and health. This will contribute to reduce uncertainty about the health status of immigrants that is required for decision- making in public health in Chile and the region.

Bone turnover and metabolism in patients with early multiple sclerosis and prevalent bone mass deficit: a population-based case-control study

Background

Low bone mass is prevalent in ambulatory multiple sclerosis (MS) patients even shortly after clinical onset. The mechanism is not known, but could involve shared etiological risk factors between MS and low bone mass such as hypovitaminosis D operating before disease onset, or increased bone loss after disease onset. The aim of this study was to explore the mechanism of the low bone mass in early-stage MS patients.

Methodology/Principal Findings

We performed a population-based case-control study comparing bone turnover (cross-linked N-terminal telopeptide of type 1 collagen; NTX, bone alkaline phosphatase; bALP), metabolism (25-hydroxy- and 1, 25-dihydroxyvitamin D, calcium, phosphate, and parathyroid hormone), and relevant lifestyle factors in 99 patients newly diagnosed with clinically isolated syndrome (CIS) or MS, and in 159 age, sex, and ethnicity matched controls. After adjustment for possible confounders, there were no significant differences in NTX (mean 3.3; 95% CI −6.9, 13.5; p = 0.519), bALP (mean 1.6; 95% CI −0.2, 3.5; p = 0.081), or in any of the parameters related to bone metabolism in patients compared to controls. The markers of bone turnover and metabolism were not significantly correlated with bone mass density, or associated with the presence of osteoporosis or osteopenia within or between the patient and control groups. Intake of vitamin D and calcium, reported UV exposure, and physical activity did not differ significantly.

Conclusions/Significance

Bone turnover and metabolism did not differ significantly in CIS and MS patients with prevalent low bone mass compared to controls. These findings indicate that the bone deficit in patients newly diagnosed with MS and CIS is not caused by recent acceleration of bone loss, and are compatible with shared etiological factors between MS and low bone mass.

The oslo health study: a dietary index estimating frequent intake of soft drinks and rare intake of fruit and vegetables is negatively associated with bone mineral density

Background. Since nutritional factors may affect bone mineral density (BMD), we have investigated whether BMD is associated with an index estimating the intake of soft drinks, fruits, and vegetables. Methods. BMD was measured in distal forearm in a subsample of the population-based Oslo Health Study. 2126 subjects had both valid BMD measurements and answered all the questions required for calculating a Dietary Index = the sum of intake estimates of colas and non-cola beverages divided by the sum of intake estimates of fruits and vegetables. We did linear regression analyses to study whether the Dietary Index and the single food items included in the index were associated with BMD. Results. There was a consistent negative association between the Dietary Index and forearm BMD. Among the single index components, colas and non-cola soft drinks were negatively associated with BMD. The negative association between the Dietary Index and BMD prevailed after adjusting for gender, age, and body mass index, length of education, smoking, alcohol intake, and physical activity. Conclusion. An index reflecting frequent intake of soft drinks and rare intake of fruit and vegetables was inversely related to distal forearm bone mineral density.

Outdoor air pollution, bone density and self-reported forearm fracture: the Oslo Health Study

Air pollution is associated with several adverse health outcomes and increased mortality. In the Oslo Health Study, an association between long-term outdoor air pollution exposure and bone health was suggested in men aged 75/76 years, but not in younger men or in women.

INTRODUCTION

Associations have been found between air pollution and a range of diseases, but few have studied whether bone health differs according to the concentration of air pollution. The aim of this study was to investigate the association between indicators of air pollution and bone health.

METHODS

Self-reported forearm fracture was assessed in men and women 75/76 and 59/60 years (n = 5,976) participating in the Oslo Health Study 2000-2001. In subsamples of the participants (n = 1,039), we studied the relation between air pollution and forearm bone mineral density (BMD) measured by single X-ray absorptiometry. Exposure to air pollution (particulate matter (PM(10) and PM(2.5)) and nitrogen dioxide (NO(2))) at each participant's home address was estimated from 1992 to 2001.

RESULTS

We found no associations between air pollution and self-reported forearm fractures or BMD in men aged 59/60 years or in women. In men aged 75/76 years, an increment of 10 units in PM(2.5) was associated with a reduction in distal forearm BMD of 64 mg/cm(2) (p < 0.05), and with an increased prevalence of forearm fracture after the age of 50 years among current smokers, OR = 7.4 (p < 0.05). Similar patterns of associations were suggested for PM(10) and NO(2).

CONCLUSIONS

In this study, bone health was not associated with long-term exposure to air pollution in women and in men 59/60 years of age. However, a negative association was suggested in elderly men. Further studies with improved measures of air pollution are warranted.

Serum phosphate, blood pressure, and the metabolic syndrome--20-year follow-up of middle-aged men

The authors investigated the relationship between serum phosphate (S-phosphate) and the metabolic syndrome in a group of middle-aged hypertensive and normotensive men during 20-year follow-up. Fifty-six men participated. Of the original 34 normotensive men, hypertension developed in 17. In the group as a whole and in those in whom hypertension developed, there was a significant negative relationship between S-phosphate at baseline and mean blood pressure (MBP) at follow-up. A significant relationship was observed between S-phosphate at baseline and components of the metabolic syndrome in the group as a whole, in individuals with hypertension, and in individuals with the lowest S-phosphate levels at follow-up. S-phosphate at baseline predicted MBP 20 years later in a group of hypertensive and normotensive men. When grouped according to the number of components of the metabolic syndrome, individuals with the lowest serum phosphate levels had the highest number of risk factors. These findings may suggest a role of low S-phosphate in the development of hypertension and the metabolic syndrome.

Differences in precision in bone mineral density measured by SXA and DXA: the NOREPOS study

The aims were to compare the precision (reliability) in single X-ray (SXA) and dual X-ray (DXA) absorptiometry, and to compare smallest detectable difference (SDD). An additional aim was to examine determinants for precision in bone mineral density (BMD). BMD was measured by SXA (DTX-100, Osteometer) in the forearm and by DXA (Lunar Expert) in the forearm and in the hip. Two measurements were performed at each site/method, and 195 of 207 participants had complete datasets. Participants were aged 47-49 and 71-74 years. The precision was estimated by Root Mean Square Standard Deviation (RMS SD) with 95% Confidence Interval (95%CI) and the corresponding coefficients of variation (CV%). Determinants (age, gender, BMD) were analysed by multiple linear regression with log (SD) and log (CV) as dependent variables. RMS SD tended to be largest in older women and in those with low BMD. RMS SD for SXA and DXA forearm was 4.6 (4.2-5.1) and 6.8 (6.1-7.4) and the corresponding CVs 1.0% and 1.4%. RMS SD for DXA hip was 11.0 (9.9-12.0) with CV 1.2%. To detect a 3% change in BMD one would need two repeated measurements by DXA in the distal forearm at each of two consultations, but only one measurement by SXA in the distal forearm and also only one measurement by DXA in the hip. Precision differed by type of densitometer affecting the number of repeated measurements needed to detect a given BMD difference.

Epidemiology of distal forearm fractures in Oslo, Norway

The population of Oslo has the highest incidence of hip fracture reported. The present study shows that the overall incidence of distal forearm fractures in Oslo is higher than in other countries and has not changed significantly when comparing the incidence of 1998/99 with 1979.

INTRODUCTION

The population of Oslo has the highest incidence of hip fracture reported. The present study reports the incidence of distal forearm fracture in Oslo and the fracture rates of immigrants.

METHODS

Patients aged > or = 20 years resident in Oslo sustaining a distal forearm fracture in a one-year period in 1998/99 were identified using electronic diagnosis registers, patient protocols, and/or X-ray registers of the clinics in Oslo. Medical records were obtained and the diagnosis verified. The age- and sex-specific incidence rates were calculated and compared with those for 1979. Data on immigrant category and country of origin of the patients were obtained.

RESULTS

The age-adjusted fracture rates per 10,000 for the age group > or = 50 years were 109.8 and 25.4 in 1998/99 compared with 108.3 and 23.5 in 1979 for women and men, respectively (n.s.). The relative risk of fracture in Asians was 0.72 (95% CI 0.53-1.00) compared with ethnic Norwegians.

CONCLUSIONS

The overall incidence of distal forearm fractures in Oslo is higher than in other countries and has not changed significantly when comparing the incidence of 1998/99 with 1979. Furthermore, the present data suggest that Asian immigrants in Oslo have a slightly lower fracture risk than ethnic Norwegians.

Pakistanis living in Oslo have lower serum 1,25-dihydroxyvitamin D levels but higher serum ionized calcium levels compared with ethnic Norwegians. The Oslo Health Study

BACKGROUND

Persons of Pakistani origin living in Oslo have a much higher prevalence of vitamin D deficiency and secondary hyperparathyroidism but similar bone mineral density compared with ethnic Norwegians. Our objective was to investigate whether Pakistani immigrants living in Oslo have an altered vitamin D metabolism by means of compensatory higher serum levels of 1,25-dihydroxyvitamin D (s-1,25(OH)2D) compared with ethnic Norwegians; and whether serum levels of ionized calcium (s-Ca2+) differ between Pakistanis and Norwegians.

METHODS

In a cross-sectional, population-based study venous serum samples were drawn from 94 Pakistani men and 67 Pakistani women aged 30-60 years, and 290 Norwegian men and 270 Norwegian women aged 45-60 years; in total 721 subjects.

RESULTS

Pakistanis had lower s-1,25(OH)2D compared with Norwegians (p < 0.001). Age- and gender adjusted mean (95% CI) levels were 93 (86, 99) pmol/l in Pakistanis and 123 (120, 126) pmol/l in Norwegians, p < 0.001. The difference persisted after controlling for body mass index. There was a positive relation between serum 25-hydroxyvitamin D (s-25(OH)D) and s-1,25(OH)2D in both groups. S-Ca2+ was higher in Pakistanis; age-adjusted mean (95% CI) levels were 1.28 (1.27, 1.28) mmol/l in Pakistanis and 1.26 (1.26, 1.26) mmol/l in Norwegians, p < 0.001. In both groups, s-Ca2+ was inversely correlated to serum intact parathyroid hormone levels (s-iPTH). For any s-iPTH, s-Ca2+ was higher in Pakistanis, also when controlling for age.

CONCLUSION

Community-dwelling Pakistanis in Oslo with low vitamin D status and secondary hyperparathyroidism have lower s-1,25(OH)2D compared with ethnic Norwegians. However, the Pakistanis have higher s-Ca2+. The cause of the higher s-Ca2+ in Pakistanis in spite of their higher iPTH remains unclear.

Forearm bone geometry and mineral content in UK women of European and South-Asian origin

Ethnic variation in areal bone mineral density (BMD) has been well documented. Such variation may, however, reflects differences in bone geometry rather than volumetric BMD (vBMD). The aim of the study was to compare bone geometry, mineral content (BMC) and vBMD in two ethnic groups, and study the influence of body size, physical activity, reproductive variables, 25 hydroxy-vitamin D (25(OH)D) and parathormone (PTH) status on any observed differences. The data were from a population-based, cross-sectional survey of peak bone mass in South Asian and European women, the population consisted 230 pre-menopausal South Asian (n=118, mean age 28.6+/-4.6 years) and European (n=112, mean age 30+/-4.3 years) women of UK origin. Women who participated completed an interviewer assisted questionnaire, had blood taken for assessment of 25(OH)D and PTH and had measurements of their distal (4%) and diaphyseal (50%) radius geometry, BMC and vBMD using peripheral quantitative computed tomography. At the 50% radius, South Asians had lower vBMD (p<0.001), BMC (p<0.001), cortical area (p<0.001), cortical thickness (p<0.001), cross-sectional area (p=0.04) and increased medullary area (p<0.04). Cross-sectional muscle area and stress strain index, however, were not different. Adjustment for age, height and weight attenuated, the difference in cross-section area but did not account for any of the other observed differences. Further adjustment for reproductive variables a physical activity index, 25(OH)D and PTH, attenuated ethnic differences in cortical BMC, area and thickness which became non-significant; however, ethnic differences in cortical vBMD and medullary area persisted. At the 4% site, after adjusting for age, height and weight, there was no difference in total area, total or trabecular vBMD between ethnic groups. After further adjustment for physical activity, reproductive variables, 25(OH)D and PTH, trabecular vBMD was higher in the South Asians. In conclusion, there are differences in bone geometry, BMC and vBMD at the radial diaphysis between UK South Asians and Europeans which are not explained by differences in body size. Polar stress-strain index was similar, however, suggesting no important differences in bone strength.

Ethnic differences in bone mineral density between inuit and Caucasians in north Greenland are caused by differences in body size

Data on bone mineral density (BMD) in living Inuit are limited and BMD measurements in Arctic Inuit using Dualenergy X-ray Absorptiometry (DXA) are lacking. Ethnicity may be important for bone mass. The aim of this study was to validate DXA in rural Arctic Greenland, to measure BMD in Greenland Inuit and Caucasians, and to estimate the importance of ethnicity for BMD. We measured the BMD in 80 healthy subjects living in Ilulissat and Saqqaq in North Greenland twice in both distal forearms and in both heels using peripheral DXA (pDXA). Participants were stratified by origin (Inuit[settlement])/Caucasians, n = 33 [19]/28), gender (men/women, n = 37/43), and age (30-39/40-49, n = 32/48). Caucasians were bigger than Inuit (men/women, height p < 0.001/p < 0.001; weight p = 0.01/ p = 0.026), but had similar BMI (p = 0.42/0.70). Triplicate pDXA measurements showed individual CV% = 0.16-1.79%; overall CV% = 1.1% (forearm)/1.0% (heel). Data followed the normal distribution (p = 0.65-0.99) with identical variances between Inuit and Caucasians (p = 0.12-0.63). Mean BMD in right forearm/left forearm/right heel/left heel was: Inuit men 0.570/0.568/0.549/0.536 g/cm2; Inuit women 0.484/0.474/0.473/0.464 g/cm2; Caucasian men 0.580/0.570/0.646/0.638 g/cm2; Caucasian women 0.495/0.496/0.552/0.553 g/cm2. An ethnic difference in heel BMD (p < 0.001) disappeared when adjusted for weight (p = 0.30). No difference was found in forearm BMD. In conclusion, pDXA is feasible and reliable in rural Greenland. Ethnic differences in BMD are small and may reflect differences in body size.