Funck-Brentano T, et al. - Via analyzing individual level data from 384,838 unrelated candidates of the UK Biobank study, researchers identified causal risk factors for knee, hip and hand osteoarthritis (OA), which is the most common form of arthritis. To test for causality for body mass index (BMI), bone mineral density (BMD), serum HDL-cholesterol, LDL-cholesterol, triglycerides, type 2 diabetes, systolic blood pressure (SBP), and C-reactive protein (CRP), Mendelian randomization analyses were performed. All OA, knee and hip OA were causally associated with low SBP. For the other metabolic factors or CRP tested, there was no evidence of causality. According to findings, BMI exerts a major causal effect on the weight-bearing joints risk of OA, but not on the hand. Evidence of causality on all knee and hip OA was observed for high BMD and low SBP, on the other hand, no evidence of causality for other metabolic factors or CRP was demonstrated.