Vitamin D Status Appears Unrelated to Fractures in Patients with Chronic Kidney Disease

Background: Although lack of Vitamin D is widespread in chronic kidney disease, data is scarce in the role Vitamin D may play in fractures in such cases.
Methods: Retrospective analysis of all patients visiting Nephrology outpatients department in 1 UK District General Hospital over 2 years. Chronic kidney disease was categorised by estimated glomerular filtration rate, total Vitamin D and fracture details obtained from Hospital Information Technology system. Total Vitamin D <50nmol/L was considered inadequate. Logistic regression was used to assess the relationships of eGFR and total Vitamin D with fracture incidence. Spearman’s correlation coefficient (rs) was used to assess the relationship between continuous variables.
Results: 43/66 patients were Vitamin D deficient - prevalence of Vitamin D deficiency was 65% (95% CI: 52%, 76%). 20/66 patients sustained any form of fracture, incidence of fracture in this chronic kidney disease population was 30% (95% CI: 20%, 43%). There was no association between total Vitamin D level and risk of fracture, OR 0.99 (95% CI: 0.97, 1.01), p = 0.316. The strength of the association between total Vitamin D level and fracture was also unrelated to estimated glomerular filtration level (interaction test, p = 0.971). There was no relationship between estimated glomerular filtration and total Vitamin D level (rs = -0.03, p = 0.8066). Estimated glomerular filtration was found to be negatively associated with risk of fracture, OR 0.96 (0.93, 1.00), p = 0.028.
Conclusion: Vitamin D deficiency appears widely prevalent in chronic kidney disease with a third of patients sustaining fractures; total Vitamin D levels however are unrelated to fractures. Prospective interventional studies can help answer if earlier replacement of Vitamin D before chronic kidney disease develops will help improve musculoskeletal health and prevent fractures.