The Gambian Bone and Muscle Ageing Study: Baseline Data from a Prospective Observational African Sub-Saharan Study

Disparities in the Prevalence of Osteoporosis and Osteopenia in Men and Women Living in Sub-Saharan Africa, the UK, and the USA

PURPOSE

To review the rising prevalence of osteopenia and osteoporosis in sub-Saharan Africa and the challenges this poses to governments and healthcare services. Using existing studies, we compare the prevalence of osteopenia and osteoporosis in men and women from sub-Saharan Africa to US and UK cohorts. Context-specific disparities in healthcare are discussed particularly the challenges in diagnosis and treatment of osteoporosis.

RECENT FINDINGS

There are few epidemiological data describing the burden of osteoporosis in sub-Saharan Africa. In the studies and cohorts presented here, osteoporosis prevalence varies by sex, country and area of residence, but is generally higher in African populations, than has previously been appreciated. Risk factors contributing to poorer bone health include HIV, malnutrition and "inflammaging." Reprioritization towards care of ageing populations is urgently required. Equitable access to implementable preventative strategies, diagnostic services, treatments and pathways of care for bone health (for example embedded within HIV services) need now to be recognized and addressed by policy makers.

Sex-specific associations between cardiovascular risk factors and physical function: the Gambian Bone and Muscle Ageing Study

BACKGROUND

In Sub-Saharan Africa, the prevalence of obesity, cardiovascular disease (CVD) and impaired physical function are increasing due to rapid urbanization. We investigated sex differences in associations between cardiac workload, arterial stiffness, peripheral vascular calcification (PVC) and physical function in Gambian adults.

METHODS

A total of 488 Gambians aged 40-75+ years were recruited (men: 239; and women: 249). Supine blood pressure and heart rate were measured to calculate rate pressure product and pulse pressure. Presence of PVC was determined from tibia peripheral quantitative computed tomography scans. Physical function was assessed by chair rise test (CRT), single two-legged jump (s2LJ) and hand grip strength (HGS). Body composition was measured by dual-energy x-ray absorptiometry; body size corrections were used to calculate fat mass index (FMI) and appendicular lean mass index (ALMI). Estimated glomerular filtration rate (eGFR) was measured from fasting blood samples. The relationship between rate pressure product, pulse pressure or presence of PVC (independent variable) with physical function parameters (dependent variable) was tested using linear regression. Sex-interactions were tested (p-int) adjusting for age, eGFR and ALMI/FMI. Results were expressed as mean differences between men and women with 95% confidence intervals. Mediation analyses used ALMI/FMI as mediator.

RESULTS

Women weighed less (54.7 kg ± 10.3 vs. 59.9 kg ± 10.3) and were shorter (157.8 cm ± 6.0 vs. 169.2 cm ± 7.0) compared with men (both P < 0.0001). Women had higher FMI (6.8 kg/m2  ± 2.9 vs. 2.9 kg/m2  ± 2.0, P < 0.0001) and eGFR (263.7 mL/min/1.73 m2  ± 133.1 vs. 237.6 mL/min/1.73 m2  ± 134.6), but lower ALMI (6.2 kg/m2  ± 0.7 vs. 8.02 kg/m2  ± 1.0, P < 0.0001) compared with men. There were significant mean differences between men and women in rate pressure product and s2LJ power (-1.08 [-1.21, -0.95]) and force (-0.57 [-0.63, -0.51]), only after adjusting for age, eGFR and FMI. There were significant mean differences in the associations between pulse pressure and CRT power (-0.28 [-0.31, -0.25]), s2LJ power (-1.07 [-1.20, -0.93]) and HGS (-11.94 [-13.35, -10.54]); these differences were greater after adjusting for age, eGFR and FMI, than ALMI. There were similar differences in the associations between PVC and physical function parameters. In men, FMI mediated the association between rate pressuree product and CRT power (P = 0.002), s2LJ force (P < 0.001) and s2LJ power (P = 0.001). ALMI did not mediate associations for either men or women.

CONCLUSIONS

Multiple risk factors for CVD were associated with poorer physical function in men and were mediated by FMI. There is a need to identify strategies to slow/prevent the rising CVD burden and poor physical function in Sub-Saharan Africa.

Longitudinal Change in Bone Density, Geometry, and Estimated Bone Strength in Older Men and Women From The Gambia: Findings From the Gambian Bone and Muscle Aging Study (GamBAS)

Musculoskeletal aging in the most resource-limited countries has not been quantified, and longitudinal data are urgently needed to inform policy. The aim of this prospective study was to describe musculoskeletal aging in Gambian adults. A total of 488 participants were recruited stratified by sex and 5-year age band (aged 40 years and older); 386 attended follow-up 1.7 years later. Outcomes were dual-energy X-ray absorptiometry (DXA) (n = 383) total hip areal bone mineral density (aBMD), bone mineral content (BMC), bone area (BA); peripheral quantitative computed tomography (pQCT) diaphyseal and epiphyseal radius and tibia (n = 313) total volumetric BMD (vBMD), trabecular vBMD, estimated bone strength indices (BSIc), cross-sectional area (CSA), BMC, and cortical vBMD. Mean annualized percentage change in bone outcomes was assessed in 10-year age bands and linear trends for age assessed. Bone turnover markers, parathyroid hormone (PTH), and 25-hydroxyvitamin D (25(OH)D) were explored as predictors of change in bone. Bone loss was observed at all sites, with an annual loss of total hip aBMD of 1.2% in women after age 50 years and in men at age 70 years plus. Greater loss in vBMD and BSIc was found at the radius in both men and women; strength was reduced by 4% per year in women and 3% per year in men (p trend 0.02, 0.03, respectively). At cortical sites, reductions in BMC, CSA, and vBMD were observed, being greatest in BMC in women, between 1.4% and 2.0% per annum. Higher CTX and PINP predicted greater loss of trabecular vBMD in women and BMC in men at the radius, and higher 25(OH)D with less loss of tibial trabecular vBMD and CSA in women. The magnitude of bone loss was like those reported in countries where fragility fracture rates are much higher. Given the predicted rise in fracture rates in resource-poor countries such as The Gambia, these data provide important insights into musculoskeletal health in this population. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Hard facts and misfits: essential ingredients of public health nutrition research

Policy decisions and the practice of public health nutrition need to be based on solid evidence, developed through rigorous research studies where objective measures are used and results that run counter to dogma are not dismissed but investigated. In recent years, enhancements in study designs, and methodologies for systematic reviews and meta-analysis, have improved the evidence-base for nutrition policy and practice. However, these still rely on a full appreciation of the strengths and limitations of the measures on which conclusions are drawn and on the thorough investigation of outcomes that do not fit expectations or prevailing convictions. The importance of ‘hard facts’ and ‘misfits’ in research designed to advance knowledge and improve public health nutrition is illustrated in this paper through a selection of studies from different stages in my research career, focused on the nutritional requirements of resource-poor populations in Africa and Asia.

Sex-Specific Associations Between Cardiac Workload, Peripheral Vascular Calcification, and Bone Mineral Density: The Gambian Bone and Muscle Aging Study

Noncommunicable diseases (NCD) are rapidly rising in Africa, with multimorbidity increasing the burden on health and social care. Osteoporosis and cardiovascular disease (CVD) share common risk factors; both often remain undiagnosed until a major life-threatening event occurs. We investigated the associations between cardiac workload, peripheral vascular calcification (PVC), and bone parameters in Gambian adults. The Gambian Bone and Muscle Aging Study (GamBAS) recruited 249 women and 239 men aged 40 to 75+ years. Body composition and areal bone mineral density (aBMD) were measured using dual-energy X-ray absorptiometry; peripheral quantitative computed tomography (pQCT) scans were performed at the radius and tibia. Supine blood pressure and heart rate were measured and used to calculate rate pressure product and pulse pressure. Presence of PVC was determined from tibia pQCT scans. Sex interactions were tested (denoted as p-int); adjustments were made for residuals of appendicular lean mass (ALM) and fat mass (FM). There were negative associations between rate pressure product and aBMD in women only, all p-int < .05; after adjustment for ALM residuals, for every 10% increase in rate pressure product, aBMD was lower at the whole body (-0.6% [-1.2, -0.1]), femoral neck (-0.9% [-1.8, -0.05]), L1 to L4 (-0.6% [-1.7, 0.5]), and radius (-1.9% [-2.8, -0.9]); there were similar associations when adjusted for FM residuals. Similar negative associations were found between pulse pressure and aBMD in women only. PVC were found in 26.6% men and 22.5% women; women but not men with calcification had poorer cardiac health and negative associations with aBMD (all sites p-int < .001). There were consistent associations with cardiac parameters and pQCT outcomes at the radius and tibia in women only. Multiple markers of cardiac health are associated with poorer bone health in Gambian women. In the context of epidemiological transition and changing NCD burden, there is a need to identify preventative strategies to slow/prevent the rising burden in CVD and osteoporosis in Sub-Saharan Africa. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Ethnic Differences in Bone Microarchitecture

PURPOSE OF THE REVIEW

The aim of this review is to briefly introduce updates in global fracture epidemiology and then to highlight recent contributions to understanding ethnic differences in bone density, geometry and microarchitecture and consider how these might contribute to differences in fracture risk. The review focuses on studies using peripheral quantitative computed tomography techniques.

RECENT FINDINGS

Recent studies have contributed to our understanding of the differences in fracture incidence both between countries, as well as between ethnic groups living within the same country. In terms of understanding the reasons for ethnic differences in fracture incidence, advanced imaging techniques continue to increase our understanding, though there remain relatively few studies. It is a priority to continue to understand the epidemiology, and changes in the patterns of, fracture, as well as the underlying phenotypic and biological reasons for the ethnic differences which are observed.

Osteoporosis in Africa-where are we now

Africa is experiencing an exponential increase in the number of older persons. The number of persons surviving with human immunodeficiency virus is simultaneously increasing due to improved availability of anti-retroviral therapy. The burden of non-communicable diseases, in particular, osteoporosis and its consequent fragility fractures, is also predicted to increase. Osteoporosis, however, remains a neglected disease and there are no age-standardized reference data available to accurately screen and diagnose individuals with osteoporosis. Epidemiological studies reporting the incidence of hip fracture or vertebral fractures are limited from Africa, especially Sub-Saharan Africa. The studies are usually limited as they are based on a retrospective data and small study numbers and often from a single study site. However, compared with early initial studies, the more recent studies show that osteoporosis and fractures are increasing across the continent. The overall incidence rates for osteoporosis and fractures still vary greatly between different regions in Africa and ethnic groups. Predisposing factors are similar with those in developed countries, but awareness of osteoporosis is sorely lacking. There is a lack of awareness among the population as well as health authorities, making it extremely difficult to quantify the burden of disease. There is great potential for research into the need and availability of preventive strategies. The FRAX® tool needs to be developed for African populations and may circumvent the shortage of bone densitometry.

Vitamin D Status Increases During Pregnancy and in Response to Vitamin D Supplementation in Rural Gambian Women

BACKGROUND

Vitamin D is important to maternal, fetal, and infant health, but quality data on vitamin D status in low- and middle-income countries and response to cholecalciferol supplementation in pregnancy are sparse.

OBJECTIVE

We characterized vitamin D status and vitamin D metabolite change across pregnancy and in response to cholecalciferol supplementation in rural Gambia.

METHODS

This study was a secondary analysis of samples collected in a 4-arm trial of maternal nutritional supplementation [iron folic acid (FeFol); multiple micronutrients (MMN); protein energy (PE) as lipid-based supplement; PE + MMN]; MMN included 10 μg/d cholecalciferol. Plasma 25-hydroxycholecalciferol [25(OH)D3], 24,25-dihydroxycholecalciferol [24,25(OH)2D3], and C3-epimer-25-hydroxycholecalciferol [3-epi-25(OH)D3] were measured by LC-MS/MS in 863 women [aged 30 ± 7 y (mean ± SD)] in early pregnancy (presupplementation) and late pregnancy, (gestational age 14 ± 3 and 30 ± 1 wk). Changes in 25(OH)D3 and vitamin D metabolite concentrations and associations with pregnancy stage and maternal age and anthropometry were tested.

RESULTS

Early pregnancy 25(OH)D3 concentration was 70 ± 15 nmol/L and increased according to pregnancy stage (82 ± 18 and 87 ± 17 nmol/L in the FeFol and PE-arms) and to cholecalciferol supplementation (95 ± 19 and 90 ± 20 nmol/L in the MMN and PE + MMN-arms) (P < 0.0001). There was no difference between supplemented groups. Early pregnancy 25(OH)D3 was positively associated with maternal age and gestational age. Change in 25(OH)D3 was negatively associated with late pregnancy, but not early pregnancy, triceps skinfold thickness. The pattern of change of 24,25(OH)2D3 mirrored that of 25(OH)D3 and appeared to flatten as pregnancy progressed, whereas 3-epi-25(OH)D3 concentration increased across pregnancy.

CONCLUSION

This study provides important data on the vitamin D status of a large cohort of healthy pregnant women in rural Africa. Without supplementation, vitamin D status increased during pregnancy, demonstrating that pregnancy stage should be considered when assessing vitamin D status. Nutritionally relevant cholecalciferol supplementation further increased vitamin D status. These data are relevant to the development of fortification and supplementation policies in pregnant women in West Africa.

The prevalence of sarcopenia and relationships between muscle and bone in ageing West-African Gambian men and women

BACKGROUND

The rapidly rising ageing population in low and middle-income countries (LMIC) will lead to a concurrent increase in musculoskeletal diseases. Sarcopenia is a disease caused by progressive loss of skeletal muscle mass and strength, leading to adverse outcomes including frailty, falls, fractures, and premature mortality. We investigated the prevalence of sarcopenia, assessed the suitability of current diagnostic guidelines and explored muscle-bone relationships in ageing men and women from rural Gambia.

METHODS

A total of 249 women and 239 men aged 40-75+ years were recruited. Body composition was measured using dual energy X-ray absorptiometry. Comparisons of the Foundations for the National Institutes of Health (FNIH) and European Working Group On Sarcopenia (EWGSOP) definitions of sarcopenia to define prevalence and to identify poor physical capability were determined. Functional ability was assessed by jumping mechanography to calculate lower limb muscle force and power; grip strength was assessed by a hand dynamometer. Peripheral quantitative computed tomography was used to assess muscle-bone relationships.

RESULTS

The prevalence of sarcopenia in Gambian men and women significantly varied depending on the definition used; in men 20% and 19% and in women 45% and 10% for FNIH and EWGSOP, respectively. The FNIH appendicular lean mass cut-off had greatest sensitivity and specificity in identifying low functional ability in Gambian adults. Muscle force was positively associated with measures of tibial bone size, strength, and mineral content.

CONCLUSIONS

The variation in the prevalence of sarcopenia depends on the definition used and highlights the importance of measuring functional capability across ethnic populations.