Aims were to assess 1.) whether odds for incident radiographic osteoarthritis (ROA) differ between men and women in regard to body mass index (BMI) and inflammatory magnetic resonance imaging (MRI) markers one and two years prior and 2.) whether presence of inflammation on MRI differs between normal-weight, and overweight/obese persons that develop ROA up to four years prior.
We studied 355 knees from the Osteoarthritis Initiative study that developed incident ROA and 355 matched controls. MRIs were read for effusion-synovitis and Hoffa-synovitis for up to four consecutive annual time points. Subjects were classified as normal-weight (BMI < 25), overweight (BMI ≥25/<30) or obese (BMI ≥30). Conditional logistic regression was used to assess odds of incident ROA for effusion-synovitis and Hoffa-synovitis at one and two years prior ROA incidence (i.e. "P-1" and "P-2") considering BMI category. Bivariate logistic regression was used to assess odds of inflammation for cases only.
178 (25.1%) participants were normal-weight, 283 (39.9%) overweight and 249 (35.1%) obese. At P-2 being overweight with Hoffa-synovitis (OR 3.26, 95%CI 1.39,7.65) or effusion-synovitis (3.56, 95%CI 1.45,8.75) was associated with greater odds of incident ROA in women. For those with incident ROA there were no increased odds of synovitis in the overweight/obese subgroup for most time points but increased odds for effusion-synovitis were observed at P-2 (OR 2.21, 95%CI 1.11,4.43).
Presence of inflammatory markers seems to play a role especially in overweight women while obese women have increased odds for ROA also in the absence of these markers.