Inflammatory status, body composition and ethnic differences in bone mineral density: The Southall and Brent Revisited Study.

Ruth Durdin,Nicholas C Harvey,Therese Tillin,Nishi Chaturvedi,Suzanne Williams,Camille Parsons,Cyrus Cooper,Elaine M Dennison,Kate A Ward

doi:10.1016/j.bone.2021.116286

Abstract

Ethnic differences in bone mineral density (BMD) and fracture risk are well-described; the aim of this study was to investigate whether central adiposity or inflammatory status contribute to these ethnic differences in BMD in later life.The Southall and Brent Revisited study (SABRE) is a UK-based tri-ethnic cohort of men and women of European, South Asian or African Caribbean origin. At the most recent SABRE follow-up (2014–2018), in addition to measures of cardiometabolic phenotype, participants had dual-energy X-ray absorptiometry (DXA) bone and body composition scans. Multiple linear regression was used to determine whether markers of body composition, central adiposity or inflammatory status contributed to ethnic differences in BMD.In men and women, age- and height-adjusted BMD at all sites was higher in African Caribbeans compared to Europeans (femoral neck: standardised β (95% confidence interval): men: 1.00SD (0.75, 1.25); women: 0.77SD (0.56, 0.99)). South Asian men had higher BMD than European men at the hip (femoral neck: 0.34SD (95%CI: 0.15, 0.54)). Although adjustment for body mass index (BMI) or lean mass index (LMI) at the lumbar spine reduced the size of the difference in BMD between African Caribbean and European men (age and height adjusted difference: 0.35SD (0.08, 0.62); age and BMI adjusted difference: 0.25SD (−0.02, 0.51)), in both men and women ethnic differences remained after adjustment for measures of central adiposity (estimated visceral adipose tissue mass (VAT mass) and android to gynoid ratio) and inflammation (interleukin-6 (logIL-6) and C-reactive protein (logCRP)). Furthermore, in women, we observed ethnic differences in the relationship between BMI (overall interaction: p = 0.04), LMI (p = 0.04) or VAT mass (p = 0.009) and standardised lumbar spine BMD.In this tri-ethnic cohort, ethnic differences in BMD at the femoral neck, total hip or lumbar spine were not explained by BMI, central adiposity or inflammatory status. Given ethnic differences in fracture incidence, it is important to further investigate why ethnic differences in BMD exist.

Highlights

Ethnic differences in fracture incidence exist in men and women in the UK, where fracture incidence is highest in White and lowest in Black individuals [1]
Median C-reactive protein (CRP) levels were higher in European men compared to South Asian men; the difference in IL-6 and CRP levels between African Caribbean and European men were of borderline significance (p = 0.05)
Based on femoral neck T-score, 5.6% of Eu ropean men and 5.5% of South Asian men were classed as having osteoporosis; there was an association between T-score and ethnicity (p < 0.01)

Summary

Introduction

Ethnic differences in fracture incidence exist in men and women in the UK, where fracture incidence is highest in White and lowest in Black individuals [1]. Previous studies of ethnic differences in bone mineral density (BMD) generally show a similar pattern with BMD being highest in Afro-Caribbean and African American, and similar in South Asian compared to Caucasian and White, men and women [2,3,4,5]. Whilst these differences are well-described, and clearly there is a strong genetic component to BMD [6], there is a need to further explore the underlying environmental determinants of the differences in BMD, especially as populations age and the risk of fracture increases. Evidence has demonstrated links be tween inflammatory markers and hip fracture in women [18,19,20], osteoporotic fractures in women [21], hip and vertebral fractures in men [22] and non-traumatic fractures in men and women [23]

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