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

Purpose: 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.

Methods: 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.

Results: 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).

Conclusion: 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.