Post-discharge kidney function is associated with subsequent ten-year renal progression risk among survivors of acute kidney injury

Simon Sawhney,Adeera Levin,David McLernon,Gordon Prescott,Angharad Marks,Nick Fluck,Corri Black

doi:10.1016/j.kint.2017.02.019

Abstract

The extent to which renal progression after acute kidney injury (AKI) arises from an initial step drop in kidney function (incomplete recovery), or from a long-term trajectory of subsequent decline, is unclear. This makes it challenging to plan or time post-discharge follow-up. This study of 14651 hospital survivors in 2003 (1966 with AKI, 12685 no AKI) separates incomplete recovery from subsequent renal decline by using the post-discharge estimated glomerular filtration rate (eGFR) rather than the pre-admission as a new reference point for determining subsequent renal outcomes. Outcomes were sustained 30% renal decline and de novo CKD stage 4, followed from 2003-2013. Death was a competing risk. Overall, death was more common than subsequent renal decline (37.5% vs 11.3%) and CKD stage 4 (4.5%). Overall, 25.7% of AKI patients had non-recovery. Subsequent renal decline was greater after AKI (vs no AKI) (14.8% vs 10.8%). Renal decline after AKI (vs no AKI) was greatest among those with higher post-discharge eGFRs with multivariable hazard ratios of 2.29 (1.88-2.78); 1.50 (1.13-2.00); 0.94 (0.68-1.32) and 0.95 (0.64-1.41) at eGFRs of 60 or more; 45-59; 30-44 and under 30, respectively. The excess risk after AKI persisted over ten years of study, irrespective of AKI severity, or post-episode proteinuria. Thus, even if post-discharge kidney function returns to normal, hospital admission with AKI is associated with increased renal progression that persists for up to ten years. Follow-up plans should avoid false reassurance when eGFR after AKI returns to normal.

Highlights

Acute kidney injury (AKI) is common and associated with poor renal outcomes,[1] but the clinical course is not well understood.[2,3,4] One reason for the increase in advanced chronic kidney disease (CKD) after acute kidney injury (AKI) is “nonrecovery,” that is, the occurrence of a step drop in estimated glomerular filtration rate during the AKI episode, which does not return to baseline once the episode has ended (Figure 1, pink dashed line)
AKI, acute kidney injury; CI, confidence interval; eGFR, estimated glomerular filtration rate; HR, hazard ratio. This large analysis of hospital survivors after AKI isolates the risk of long-term subsequent progression of kidney disease from progression that has already arisen because of an initial step drop in kidney function
When this novel approach was used, AKI during a hospital admission was associated with increased subsequent renal progression irrespective of how progression was defined, irrespective of proteinuria or AKI severity, and even if post-episode kidney function was normal

Summary

Introduction

Acute kidney injury (AKI) is common and associated with poor renal outcomes,[1] but the clinical course is not well understood.[2,3,4] One reason for the increase in advanced chronic kidney disease (CKD) after AKI (vs. no AKI) is “nonrecovery,” that is, the occurrence of a step drop in estimated glomerular filtration rate (eGFR) during the AKI episode, which does not return to baseline once the episode has ended (Figure 1, pink dashed line). We hypothesized that more patients with AKI (vs. no AKI) would experience ongoing renal decline (a 30% eGFR drop), resulting in more patients with AKI having CKD stage 4

Methods

Results

Conclusion