Two samples were Mendelian randomized to analyze the association between serum vitamin D and frozen shoulder risk

Background: In recent years, epidemiological studies have shown that vitamin D is a risk factor for frozen shoulder (FS), but whether there is a causal association between vitamin D and FS remains unknown. Objective: To explore the causal relationship between vitamin D and FS, in order to provide a theoretical basis for clinical prevention and treatment. Methods: We used pooled statistics from genome-wide association studies (GWAS) to assess a causal relationship between serum vitamin D levels (sample size = 417,580, IEU Open GWAS) and FS (sample size = 451,099, IEU Open GWAS). The main MR analysis method is the inverse variance-weighted method (IVW), supplemented by MR-Egger and weighted median. Second, we performed sensitivity analyses to verify the reliability of the results, examined for horizontal pleiotropy, and used a stay-one-assay to determine if there were potentially impactful single nucleotide polymorphisms. Results: The results showed that MR analysis did not reveal a significant causal relationship between serum 25(OH)D level y and FS risk (OR=1.0108, 95%CI: 0.8218-1.2432, P=0.9185). Conclusion: In summary, this study found no clear evidence of a causal relationship between serum vitamin D levels and the risk of FS. We call for larger sample size studies to further uncover potential causal relationships.