BMI a causal factor for osteoarthritis at weight-bearing joints

High body mass index (BMI) is causally associated with the risk of osteoarthritis (OA) at the knee and hip but not at the hand, a study has found.

Researchers used data from the UK Biobank study involving 384,838 unrelated participants. They performed Mendelian randomization (MR) analyses to test for causality for BMI, bone mineral density (BMD), serum high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride levels, type 2 diabetes, systolic blood pressure (SBP), and C-reactive protein (CRP) levels.

A total of 48,431 participants had all-site OA, whereas 19,727 had knee OA, 11,875 had hip OA and 2,330 had hand OA. On MR analyses, genetically determined BMI had a strong causal association with all-site (odds ratio [OR] per standard deviation [SD] increase, 1.57, 95 percent CI, 1.44–1.71), knee (OR, 1.76, 1.56–1.99) and hip OA (OR, 1.52, 1.31–1.78) but not hand OA.

A similar pattern of association was observed between genetically determined femoral neck BMD and all-site (OR, 1.14, 1.06–1.22), knee (OR, 1.18, 1.05–1.32) and hip OA (OR, 1.22, 1.09–1.35) but not hand OA.

Low SBP was also causally associated with all-site (OR, 0.64, 0.54–0.77), knee (OR, 0.66, 0.57–0.77) and hip OA (OR, 0.63, 0.48–0.82). There was no evidence of causality for the other tested metabolic factors or CRP level.

The present data may be used for future investigations in OA, including the prevention or therapeutic strategies for the different OA locations, the researchers said.