Predicted risk of renal replacement therapy at arteriovenous fistula referral in chronic kidney disease.

BACKGROUND AND OBJECTIVES: Optimal timing of arteriovenous fistula placement in chronic kidney disease remains difficult and contributes to high central venous catheter use at initial hemodialysis. We tested whether a prediction model for progression to renal replacement therapy developed at Kaiser Permanente Northwest may help guide decisions about timing of referral for arteriovenous fistula placement.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: A total of 205 chronic kidney disease stage 4 patients followed by nephrology referred for arteriovenous fistula placement were followed for up to 2 years. Patients were censored if they died or discontinued Kaiser Permanente Northwest coverage. Survival analyses were performed for overall progression to renal replacement therapy divided by quartiles based on 2-year risk for renal replacement therapy and estimated glomerular filtrate rate at time of referral.

RESULTS: By 2 years, 60% progressed to renal replacement therapy and 11% had died. 80% in the highest risk versus 36% in the lowest risk quartile progressed to renal replacement therapy (predicted risk 84% vs 17%). 75% in the lowest estimated glomerular filtrate rate versus 56% in the highest estimated glomerular filtrate rate quartile progressed to renal replacement therapy (mean estimated glomerular filtrate rate 13 mL/min vs 21 mL/min). The hazard ratio was significantly higher for each consecutive higher renal replacement therapy quartile risk while for estimated glomerular filtrate rate, the hazard ratio was only significantly higher for the lowest compared to the highest quartile. The extreme quartile risk ratio was higher for 2-year risk for renal replacement therapy compared to estimated glomerular filtrate rate (4.0 vs 2.4).

CONCLUSION: In patients with chronic kidney disease stage 4 referred for arteriovenous fistula placement, 2-year renal replacement therapy risk better discriminated progression to renal replacement therapy compared to estimated glomerular filtrate rate at time of referral.