title: Do synovial leptin levels correlate with pain in end stage arthritis?
abstract: OBJECTIVE
  We evaluated whether synovial fluid (SF) leptin concentrations correlate with pain severity in patients with hip or knee endstage osteoarthritis (OA) and whether they mediate the association between increased joint pain and (1) female gender and (2) obesity.
  
  
  METHODS
  We conducted a cross-sectional study including patients with primary hip and knee OA undergoing joint replacement between January and December 2010. SF leptin concentrations obtained on the day of surgery were assessed. Main outcome was pain severity measured pre-operatively using WOMAC and VAS pain scales.
  
  
  RESULTS
  A total of 219 patients were included, 123 hip and 96 knee arthroplasties. Mean age was 72 years, 59% were women. Mean SF leptin levels were 22.9 (±25.6) ng/ml in women and 5.4 (±5.9) ng/ml in men. Levels >19.6 ng/ml (highest quartile) were significantly associated with increased pain on both WOMAC (mean difference -9.6, 95% CI -15.1 to -4.0) and VAS scale (mean difference 0.8, 95% CI 0.2-1.3). Associations remained unchanged after adjusting for age, co-morbidities, contra-lateral arthritic joint, OA site, and disability. The associations observed between increased pain and female gender or obesity were substantially reduced after adjusting for SF leptin.
  
  
  CONCLUSIONS
  Joint pain is associated with SF leptin concentrations. Increased pre-operative pain observed in women and obese may be related to high intra-articular leptin levels.
authors.affiliation: Division of Orthopaedics and Trauma Surgery, University of Geneva and Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1211, Genève, Switzerland, anne.lubbekewolff@hcuge.ch.
authors.forename: Anne
authors.initials: A
authors.lastname: Lübbeke
authors.forename: Axel
authors.initials: A
authors.lastname: Finckh
authors.forename: Gabor J
authors.initials: GJ
authors.lastname: Puskas
authors.forename: Domizio
authors.initials: D
authors.lastname: Suva
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lädermann
authors.forename: Sylvette
authors.initials: S
authors.lastname: Bas
authors.forename: Daniel
authors.initials: D
authors.lastname: Fritschy
authors.forename: Cem
authors.initials: C
authors.lastname: Gabay
authors.forename: Pierre
authors.initials: P
authors.lastname: Hoffmeyer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000175:diagnosis* / Q000209:etiology; D015415:Biomarkers / Q000378:metabolism; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D020738:Leptin / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D015207:Osteoarthritis, Hip / Q000150:complications*; D020370:Osteoarthritis, Knee / Q000150:complications*; D010147:Pain Measurement; D012720:Severity of Illness Index; D012737:Sex Factors; D013582:Synovial Fluid / Q000378:metabolism*; D013583:Synovial Membrane / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D020738:Leptin