Mendelian randomization studies do not support the causal relationships between iron status and Intervertebral disc degeneration

1. Introduction Context:Intervertebral disc degeneration (IVDD) is an important contributor of low back pain, which represents one of the most disabling symptoms within the adult population.Recently, increasing evidence suggests the potential association between iron status and IVDD. However, the causal relationship between these two common diseases remains unclear.We investigated the causal effects of four iron metabolism markers, regular iron supplementation and IVDD. 2. Methods: We conducted a two-sample Mendelian randomization (MR) analysis to assess the causal association between iron status and IVDD[1]. Sensitivity analysis was performed to test for heterogeneity and horizontal pleiotropy. 3. Results The genetically instrumented iron (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 0.97–1.11; P=0.27)； ferritin(OR: 1.17; 95% CI: 0.99–1.38; P=0.07)； Liver iron content (OR: 1.04; 95% CI: 0.98–1.11; P=0.22)；Tranferrein(OR: 0.99; 95% CI: 0.91–1.08; P=0.85)；Tranferrein stautas (OR:1.02; 95% CI: 0.98–1.08; P=0.34)or supplement iron(OR:0.91; 95% CI: 0.79–1.05; P=0.18) showed no causal relationships with IVDD.No pleiotropic bias was found in the MR analyses. As heterogeneity was significant, a random model was used to minimize the effect of heterogeneity. 4. Conclusions No causal associations existed between iron status and IVDD. iron status and IVDD may represent separate entities.