The risk of new fragility fractures in patients with chronic kidney disease and hip fracture-a population-based cohort study in the UK

Chronic kidney disease (CKD) is a risk factor for fractures. However, in hip fracture patients, CKD G3-G5 was associated with a higher mortality risk and not associated with a higher risk of subsequent non-hip fractures compared to eGFR > 60 ml/min. The higher mortality risk may, as competing risk, explain our findings.

INTRODUCTION: Chronic kidney disease (CKD) is a known risk factor for fragility fractures. Patients aged 50+ with a recent fragility fracture have an increased risk of subsequent fractures. Our aim was to evaluate the association between CKD stages G3-G5 versus estimated glomerular filtration rate (eGFR) > 60 ml/min and the risk of a new non-hip fracture or fragility fracture in patients with a first hip fracture.

METHODS: Population-based cohort study using the UK general practices in the Clinical Practice Research Datalink. Associations between CKD stage and first subsequent fracture were determined using Cox proportional hazard analyses to estimate hazard ratios (HRs). To explore the potential competing risk of mortality, cause-specific (cs) HRs for mortality were estimated.

RESULTS: CKD G3-G5 was associated with a lower risk of any subsequent non-hip fracture (HR: 0.90, 95%CI: 0.83-0.97), but not with the risk of subsequent major non-hip fragility fracture. CKD G3-G5 was associated with a higher mortality risk (cs-HR: 1.05, 95%CI: 1.01-1.09). Mortality risk was 1.5- to 3-fold higher in patients with CKD G4 (cs-HR: 1.50, 95%CI: 1.38-1.62) and G5 (cs-HR: 2.93, 95%CI: 2.48-3.46) compared to eGFR > 60 ml/min.

CONCLUSIONS: The risk of a subsequent major non-hip fragility fractures following hip fracture was not increased in patients with CKD G3-G5 compared to eGFR > 60 ml/min. Mortality risk was higher in both hip fracture and non-hip fracture patients with CKD G4 and G5. The higher mortality risk may, as competing risk, explain our main finding of no increased or even decreased subsequent fracture risk after a hip fracture in patients with CKD G3-G5.