Exploring the association between adiposity, pain intensity, and effusion-synovitis in people with knee osteoarthritis: A cross-sectional study.

OBJECTIVES To examine (i) the association of adiposity with pain intensity and/or effusion-synovitis in people with knee osteoarthritis (OA), adjusting for body mass index (BMI), and (ii) whether indicators of systemic immune inflammation (i.e., the systemic immune-inflammation index (SII) and the systemic immune response index (SIRI)) moderate the above associations.

METHODS Individuals with knee OA were sampled from the Western Ontario Registry for Early Osteoarthritis Knee Study. Total body and visceral fat percentages were measured using bioimpedance analysis, and effusion-synovitis was graded using knee ultrasonography. Multiple regression models with interaction terms were used to examine the association between fat percentages and pain intensity (linear)/effusion-synovitis (logistic), and the interaction effect of fat and SII/SIRI on pain intensity/effusion-synovitis. The analyses were adjusted for confounders (age, sex, BMI, radiographic severity of the opposite knee, and anxio-depressive symptoms).

RESULTS Data from 225 participants (mean age: 61.1 (10.9), 68% female, mean BMI: 31.7 (7.7)) were analyzed. The associations for adjusted fat and pain intensity models were as follows: total body fat: β): - 0.03 (-0.54 to 0.46) and visceral fat: β (: -0.25 (-1.03 to 0.51)., The odds ratios for adjusted fat and effusion-synovitis models were total body fat: OR): 0.98 (0.92 to 1.05) and visceral fat: OR (): 1.01 (0.91 to 1.11)). Neither the main nor the interaction effects were significant.

CONCLUSION Our preliminary results do not support an association of adiposity and its interaction with generalized inflammation with pain/effusion-synovitis adjusted for BMI. Further studies are needed.