Rural Versus Nonrural Differences in BMC, Volumetric BMD, and Bone Size: a Population-based Cross-sectional Study

Document Type

Article

Publication Date

12-2004

Keywords

Adult, Aged, Bone Density, Cross-Sectional Studies, Female, Humans, Life Style, Male, Middle Aged, Rural Population, South Dakota, Suburban Population, Urban Population

Abstract

Despite reports of lower fracture risk among rural versus urban populations, few studies have investigated rural versus urban differences in bone mineral content (BMC) and bone mineral density (BMD). Population differences in cross-sectional bone geometry and understanding lifestyle factors responsible for these differences may reveal insights into the reason for differences in fracture risk. We hypothesized that if lifestyle differences in bone mass, size, and geometry are a result of muscle strength, activity, or dietary differences, Hutterite and rural populations should have greater bone mass compared to nonrural populations. The study population consisted of 1189 individuals: 504 rural Hutterites (188 men), 349 rural individuals (>75% life farming, 184 men), and 336 nonrural individuals (never lived on farm, 134 men) aged 20 to 66 years. BMC, bone area, and areal BMD (aBMD) of the total body (TB), hip, femoral neck (FN), and spine by DXA; volumetric BMD (vBMD) and bone geometry at the 4% and 20% radius; polar stress strain index (pSSI), a measure of bone strength, at the 20% pQCT site; and strength, 7-day activity recall, and 24-h diet recall were collected and compared among groups. Hutterite women and men had greater grip strength compared to rural and nonrural populations (both, P < 0.001). Rural women had greater activity versus Hutterite and nonrural (P < 0.001), while both Hutterite and rural men had greater activity than nonrural (P < 0.001). Hutterite and rural populations tended to have greater BMC and areal size than the nonrural population, while Hutterites had greater BMC and areal size than rural population at some (TB, FN for females only), but not all (proximal hip), sites. Cortical vBMD was inversely associated with periosteal circumference at the 20% radius in women (r = −0.25, P < 0.001) and men (r = −0.28, P < 0.001) and was higher in nonrural versus Hutterite and rural men. Hutterite and rural women and men had greater pSSI at the 20% radius compared to nonrural; inclusion of strength measurements explained population differences among women, but not men. Lifestyle differences did not explain population differences in BMC, aBMD, vBMD, or bone size.

Publication Title

Bone

Volume

35

Issue

6

First Page

1389

Last Page

1398

DOI of Published Version

10.1016/j.bone.2004.09.005

PMID

15589221

Publisher

Elsevier Science

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