Even Patients Whose Kidney Function Returns to Normal after AKI Have High Risk of Renal Progression

For patients who have had acute kidney injury (AKI), the long-term risk of renal progression remains high even if their kidney function ultimately returns to normal, suggests a new study in Kidney International.

Using data from one UK health region, the researchers identified 14,651 patients who survived to hospital discharge in 2003. Of these 1966 patients had stage 1 to 3 AKI, based on KDIGO criteria. Follow-up data to 2013 were used to assess rates of subsequent renal decline, defined as a sustained 30% decline in eGFR or de novo stage 4 chronic kidney disease. These outcomes were compared for patients with versus without AKI, and for AKI patients at differing levels of postdischarge kidney function.

During follow-up, 37.5% of patients died, 11.3% had sustained decline in eGFR, and 4.5% developed stage 4 CKD. Kidney function declined by at least 30% from the prehospital to posthospital period in 25.7% of AKI patients (nonrecovery), compared to 2.3% of patients without AKI.

Rates of subsequent renal decline were 14.8% in AKI survivors and 11.3% in those without AKI. This risk was greatest for AKI patients with a postdischarge eGFR of 60 mL/min/1.73 m2 or higher: multivariate hazard ratio 2.29. The excess risk associated with AKI persisted throughout the 10-year follow-up period, regardless of AKI severity or post-episode proteinuria.

It has been unclear whether the risk of renal progression after AKI is different for patients who do and do not have “recovery” of kidney function. The new study suggests that AKI survivors are at increased risk of renal progression up to 10 years after discharge, even if they regain normal kidney function. The researchers conclude, “Follow-up plans should avoid false reassurance when eGFR after AKI returns to normal.”

References

1. Sawhney S, et al. Post-discharge kidney function is associated with subsequent ten-year renal progression risk among survivors of acute kidney injury. Kidney Int 2017; doi: 10.1016/j.kint.2017.02.019.