Chronic Kidney Disease After Acute Kidney Injury Requiring Continuous Renal Replacement Therapy and Its Impact on Long-Term Outcomes: A Multicenter Retrospective Cohort Study in Korea*

OBJECTIVES: Severe acute kidney injury requiring continuous renal replacement therapy is associated with a high risk of early mortality. Our objectives were to identify a cohort of early survivors and to follow their renal progress and long-term mortality. DESIGN: Multicenter, observational, retrospective cohort study. SETTING: ICUs in tertiary academic hospitals in Korea. PATIENTS: From 2009 to 2013, we identified 1,764 severe acute kidney injury patients who were started on continuous renal replacement therapy at four hospitals. Of these, we identified 331 survivors for whom we could identify renal function at baseline and at 3 months. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The 331 patients were separated into two groups based on their renal function at 3 months after the start of continuous renal replacement therapy. Those who displayed significant deterioration in renal function compared to baseline, defined as greater than or equal to 50% increase in serum creatinine or greater than or equal to 35% decrease in the estimated glomerular filtration rate, or those who continued to receive renal replacement therapy were designated as a "3-month chronic kidney disease progression" group. Those with a return to baseline, less than 50% increase in serum creatinine or less than 35% decrease in the estimated glomerular filtration rate, were designated as a "3-month chronic kidney disease nonprogression" group. The acute kidney injury patients requiring continuous renal replacement therapy showed a higher risk of progression to end-stage renal disease compared to that of stage 3 chronic kidney disease patients who did not undergo an acute kidney injury episode, even if the acute kidney injury was recovered at 3 months after continuous renal replacement therapy initiation. Furthermore, "3-month chronic kidney disease progression" was associated with a high risk of progression to end-stage renal disease and long-term mortality over a median follow-up period of 12.7 (3.8-33.2) and 20.4 (7.5-39.7) months, respectively. Older age, higher baseline serum creatinine levels, and higher blood urea nitrogen concentrations at continuous renal replacement therapy initiation, and lower 24-hour urine output after continuous renal replacement therapy initiation are associated with an increased risk of "3-month chronic kidney disease progression." CONCLUSIONS: Renal functional assessment at 3 months after continuous renal replacement therapy initiation can be useful in predicting progression to end-stage renal disease and long-term mortality. Furthermore, continuous close monitoring and management of acute kidney injury patients requiring continuous renal replacement therapy are required, even in those with recovered renal function.