Risk of fracture in adults on renal replacement therapy: a Danish national cohort study

Patients on dialysis treatment or living with a transplanted kidney have several risk factors for bone fracture, especially disturbances in mineral metabolism and immunosuppressive therapy. We describe the incidence of fracture in this retrospective national Danish cohort study and explore the influence of age, gender, comorbidity and prescribed medication. By individual-level linkage between nationwide administrative registries, the risk of fracture was compared between the group of patients receiving chronic dialysis treatment and patients receiving their first renal transplant in the study period, using the Danish background population as reference group. All three groups were followed up until first fracture, emigration, death or end of study. Cox proportional hazard models with fracture as outcome were fitted to the data. The hazard ratio (HR) for any fracture was 3.14 [95% confidence interval (95% CI):2.97-3.31] in the dialysis group and 1.94 (95% CI: 1.72-2.18) in the renal transplanted group. The HR remained increased, but was modified by adjustment for age, gender, comorbidity and prior fracture [dialysis group: 1.85 (95% CI: 1.75-1.95); renal transplanted group: 1.82 (95% CI: 1.62-2.06)]. Prescribed diuretics, lipid-modifying agents and proton pump inhibitors also modulated the fracture risk. Patients on dialysis or living with a transplanted kidney have a significantly higher risk of fracture than the Danish background population. Differences in age, gender, drug use and comorbidity only partly explain this increased risk. Further studies are warranted to explore the reason for this increased fracture risk in patients on renal replacement therapy.