The association between leptin, interleukin-6, and hip radiographic osteoarthritis in older people: a cross-sectional study.
BACKGROUND
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 (beta=0.046 per microg/L, P=0.024 for superior; beta=0.068 per microg/L, P=0.004 for axial compartment) and IL-6 only in females (beta=0.241 per pg/ml, P=0.002 for superior; beta=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.
Stannus
Oliver P
OP
Menzies Research Institute, University of Tasmania, Private Bag 23, Hobart, Tasmania 7000, Australia.
Jones
Graeme
G
Quinn
Stephen J
SJ
Cicuttini
Flavia M
FM
Dore
Dawn
D
Ding
Changhai
C
D000368:Aged; D015415:Biomarkers / Q000097:blood; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015207:Osteoarthritis, Hip / Q000097:blood* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011859:Radiography; D012720:Severity of Illness Index; D012727:Sex Characteristics
D015415:Biomarkers; D015850:Interleukin-6; D020738:Leptin