Anemia and Long-Term Renal Prognosis in Patients with Post-Renal Acute Kidney Injury of Nonmalignant Cause.

BACKGROUND/AIMS: The renal prognosis of post-renal acute kidney injury (PoR-AKI) has not been verified so far. The objective of this study was to assess the association of baseline anemia with long-term renal prognosis in patients with PoR-AKI.

METHODS: We performed a multicenter retrospective cohort study. Consecutive adult patients from December 2006 to February 2010, who met the requirements as mentioned in the definition of PoR-AKI, were included. Patients without data on baseline renal function and at 6 months after PoR-AKI were excluded. We set baseline hemoglobin (Hb) level (g/dl) as the main exposure to be tested. The main outcome measure was long-term renal prognosis as determined by the difference between proximate estimated glomerular filtration rate (eGFR) at 6 months after diagnosis of PoR-AKI and baseline eGFR prior to the occurrence of the present PoR-AKI (ΔeGFR after 6 months) using the general linear model.

RESULTS: We included 136 patients with PoR-AKI. The most frequent cause of PoR-AKI was malignancy, accounting for 39.0% (n = 53) of cases. Multivariate analysis adjusted for possible confounders showed that ΔeGFR after 6 months significantly changed by -4.28 ml/min/1.73 m2 for every 1 g/dl lower Hb at diagnosis (95% CI 1.86-6.69, p < 0.01). An additional multivariate analysis that was stratified by the presence or absence of malignancy as the cause of PoR-AKI yielded the same significant result only in the stratum of the nonmalignant cause of PoR-AKI.

CONCLUSION: Patients with a nonmalignant cause of PoR-AKI who have baseline anemia may have poor long-term renal prognosis. In these cases, close observation of renal function after renal recovery may be required.