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The relationship between cumulative lifetime ultraviolet radiation exposure, bone mineral density, falls risk and fractures in older adults

Summary: Data linking cumulative lifetime vitamin D status with skeletal outcomes are lacking. We show that increasing cumulative sun exposure was associated with higher bone mineral density in younger males and protective against fractures in females independent of current vitamin D. This supports the concept that cumulative sun exposure is an important contributor to skeletal health.

Introduction: While low 25-hydroxyvitamin D levels are associated with increased fracture risk, this reflects only recent sun exposure. The Beagley-Gibson (BG) method utilises microtopographical skin changes to quantify cumulative lifetime ultraviolet radiation (sun) exposure. This study aimed to describe the relationship between BG grade, BMD, falls risk and fractures in older adults.

Methods: Eight hundred thirty-five community-dwelling adults aged 53-83 years had silicone casts from the dorsum of both hands graded by the BG method. BMD was measured using DXA and falls risk using the short form of the Physiological Profile Assessment. Vertebral deformities and symptomatic fractures were assessed by DXA and questionnaire, respectively.

Results: The relationship between BG grade, spine BMD and vertebral fracture varied depending upon sex. In females, increasing grade was associated with lower vertebral fracture prevalence (OR = 0.44/grade, p = 0.018) and fewer fractures (OR = 0.82/grade, p = 0.021), particularly major fractures (OR = 0.75/grade, p = 0.03). In males, increasing grade was associated with more DXA-detected vertebral deformities (RR = 1.28/grade, p = 0.001), but not symptomatic fractures. These relationships were independent of BMD, falls risk, smoking and current 25-hydroxyvitamin D. BG grade was not associated with falls risk. For BMD, there were interactions between BG grade and both age and sex and a positive trend with hip BMD in younger males.

Conclusions: BG grade demonstrated beneficial associations with fracture outcomes in females and BMD in younger males independent of current 25-hydroxyvitamin D. These data support the concept that cumulative ultraviolet radiation exposure is an important determinant of skeletal health. The association with vertebral deformities in males may reflect outdoor physical trauma in younger life.

History

Publication title

Osteoporosis International

Volume

28

Issue

7

Pagination

2061-2068

ISSN

0937-941X

Department/School

Menzies Institute for Medical Research

Publisher

Springer-Verlag London Ltd

Place of publication

Sweetapple House Catteshall Road, Godalming, England, Surrey, Gu7 3Dj

Rights statement

Copyright International Osteoporosis Foundation and National Osteoporosis Foundation 2017

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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