Chronic kidney disease and mortality in fragility fracture patients: revisiting GFR thresholds

Chronic kidney disease (CKD) is common in older adults. Still, its significance in patients with fragility fractures remains unclear, as does the clinical relevance of only mild-to-moderate CKD (GFR of 45-59 ml/min/1.73 m²) in older adults in general. We investigated how different eGFR categories (< 45, 45-59, and ≥ 60 ml/min/1.73 m²) are associated with mortality and functional outcomes in orthogeriatric patients.

This retrospective cohort study included 453 consecutive patients admitted to an orthogeriatric unit from 2015 to 2023. Estimated glomerular filtration rate (eGFR) at admission was categorized into < 45, 45-59, and ≥ 60 ml/min/1.73 m². Outcomes included mortality (via Kaplan-Meier curves, regression, and ROC analysis), in-hospital complications, and functional recovery. Mediation by frailty was also analyzed.

Patients had a mean age of 82.9 ± 6.8 years; 74.8% were female. CKD was prevalent: 52.4% had eGFR < 60, and 33.6% had eGFR < 45 ml/min/1.73 m². Those with eGFR < 45 ml/min/1.73 m² had worse baseline functional status, more comorbidities, and poorer recovery. The 45-59 group showed similar or better outcomes than those with eGFR ≥ 60 ml/min/1.73 m², including mortality. Long-term all-cause mortality was significantly higher in the < 45 ml/min/1.73 m² group (HR 1.77, 95% CI 1.25-2.51), but not in the 45-59 ml/min/1.73 m² group (HR 1.01, 95% CI 0.64-1.58).

In orthogeriatric patients, an eGFR < 45 ml/min/1.73 m² identifies individuals at higher risk of poor outcomes. However, eGFR 45-59 is not associated with adverse prognosis and may not warrant classification as CKD in this context. A lower diagnostic threshold may better reflect clinical realities in this population.