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Open Access Research article

The association between leptin, interleukin-6, and hip radiographic osteoarthritis in older people: a cross-sectional study

Oliver P Stannus1, Graeme Jones1, Stephen J Quinn1, Flavia M Cicuttini2, Dawn Dore1 and Changhai Ding12*

Author Affiliations

1 Menzies Research Institute, University of Tasmania, Private Bag 23, Hobart, Tasmania 7000, Australia

2 Department of Epidemiology and Preventive Medicine, Monash University, 89 Commercial Road, Melbourne 3004, Australia

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Arthritis Research & Therapy 2010, 12:R95  doi:10.1186/ar3022

Published: 19 May 2010

Abstract

Introduction

The associations between leptin, interleukin (IL)-6, and hip radiographic osteoarthritis (OA) have not been reported, and their roles in obesity-related hip OA are unclear. The aim of this study was to describe the associations between leptin, IL-6, and hip radiographic osteoarthritis (ROA) in older adults.

Methods

A cross-sectional sample of 193 randomly selected subjects (mean age, 63 years; range, 52 to 78 years; 48% female subjects) were studied. Hip ROA, including joint-space narrowing (JSN) and osteophytes, was determined by anteroposterior radiograph. Serum levels of leptin and interleukin (IL)-6 were measured with radioimmunoassay. Fat mass was measured with dual-energy x-ray absorptiometry (DXA). Body mass index (BMI) and waist-to-hip ratio (WHR) were calculated.

Results

In multivariable analysis, hip JSN was associated with serum levels of leptin in the whole sample (β = 0.046 per μg/L, P = 0.024 for superior; β = 0.068 per μg/L, P = 0.004 for axial compartment) and IL-6 only in females (β = 0.241 per pg/ml, P = 0.002 for superior; β = 0.239 per pg/ml, P = 0.001 for axial compartment). The positive associations between body-composition measures (BMI, WHR, percentage total fat mass, and percentage trunk fat mass) and hip JSN in women became nonsignificant after adjustment for leptin but not for IL-6. No significant associations were found between leptin, IL-6, and the presence or severity of osteophytes.

Conclusions

This study suggests that metabolic and inflammatory mechanisms may play a role in the etiology of hip OA and that the associations between body composition and hip JSN are mediated by leptin, particularly in women.