The effect of interactions between BMI and sustained depressive symptoms on knee osteoarthritis over 4 years: data from the osteoarthritis initiative

Background To assess the compound effects of BMI and sustained depressive symptoms on changes in knee structure, cartilage composition, and knee pain over 4 years using statistical interaction analyses. Methods One thousand eight hundred forty-four individuals from the Osteoarthritis Initiative Database were analyzed at baseline and 4-year follow-up. Individuals were categorized according to their BMI and presence of depressive symptoms (based on the Center for Epidemiological Studies Depression Scale (threshold≥16)) at baseline and 4-year follow-up. 3 T MRI was used to quantify knee cartilage T 2 over 4 years, while radiographs were used to assess joint space narrowing (JSN). Mixed effects models examined the effect of BMI-depressive symptoms interactions on outcomes of cartilage T 2 , JSN, and knee pain over 4-years. Results The BMI-depressive symptoms interaction was significantly associated with knee pain ( p < 0.001) changes over 4 years, but not with changes in cartilage T 2 ( p = 0.27). In women, the BMI-depressive symptoms interaction was significantly associated with JSN ( p = 0.01). In a group-based analysis, participants with obesity and depression had significantly greater 4-year changes in knee pain (coeff. (obesity + depression vs. no_obesity + no_depression) = 4.09, 95%CI = 3.60–4.58, p < 0.001), JSN (coeff. = 0.60, 95%CI = 0.44–0.77, p < 0.001), and cartilage T 2 (coeff. = 1.09, 95%CI = 0.68–1.49, p < 0.001) than participants without depression and normal BMI. Conclusions The compound effects of obesity and depression have greater impact on knee pain and JSN progression compared to what would be expected based on their individual effects.