Renal recovery after acute kidney injury: choice of initial renal replacement therapy modality still matters

Impact of renal replacement therapy on survival in patients with KDIGO stage 3 acute kidney injury: A propensity score matched analysis

AIM

To investigate the impact of renal replacement therapy (RRT) on 90-day mortality in critically ill patients suffering from KDIGO stage 3 acute kidney injury (AKI) with or without life-threatening complications using propensity score matching analysis.

METHODS

We conducted a retrospective analysis of critically ill adult patients with KDIGO Stage 3 AKI with or without RRT during ICU stay between 1/1/2011-31/12/2013. Cox regression analysis and propensity score matching methods were used to determine predictors for 90-day mortality.

RESULTS

Among 661 patients, 50.5% received RRT. The unadjusted 90-day mortality rate was 42.5% and 54.1% in patients who had or had not received RRT, respectively. After adjustment with propensity score based on the probability of receiving RRT, the cox regression analysis showed that RRT was associated with a lower 90-day mortality (p<0.001). Among 322 propensity-matched pairs, RRT was associated with lower ICU (23.6% vs. 39.8%, p=0.002), hospital (33.5% vs. 55.9%, p<0.001) and 90-day mortality (34.2% vs. 58.4%, p<0.001), and a higher 90-day renal recovery rate (57.8% vs. 45.3% full recovery, p=0.026) compared with no RRT. When an alternate propensity model was used, the benefits associated with RRT were very similar, except 90-day renal recovery became insignificant.

CONCLUSION

Our observational study found that in critically ill patients with KDIGO Stage 3 AKI, RRT may be associated with lower 90-day mortality. The benefit of RRT on renal recovery was less prominent. Medical futility and practice variations may complicate study interpretation. To avoid these limitations, large-scale multicenter, non-observational study is recommended.

Renalase contributes to the renal protection of delayed ischaemic preconditioning via the regulation of hypoxia-inducible factor-1α

Ischaemic preconditioning (IPC) attenuates acute kidney injury (AKI) from renal ischaemia reperfusion. Renalase, an amine oxidase secreted by the proximal tubule, not only degrades circulating catecholamines but also protects against renal ischaemia reperfusion injury. Here, it has been suggested that the renoprotective effect of renal IPC is partly mediated by renalase. In a model of brief intermittent renal IPC, the increased cortex renalase expression was found to last for 48 hrs. IPC significantly reduced renal tubular inflammation, necrosis and oxidative stress following renal ischaemia reperfusion injury. Such effects were attenuated by blocking renalase with an anti-renalase monoclonal antibody. We further demonstrated that renalase expression was up-regulated by hypoxia in vitro via an hypoxia-inducible factor (HIF)-1α mechanism. The IPC-induced up-regulation of renalase in vivo was also reduced by pre-treatment with an HIF-1α inhibitor, 3-(5′-Hydroxymethyl-2′-furyl)-1-benzyl indazole. In summary, the renoprotective effect of IPC is partly dependent on the renalase expression, which may be triggered by hypoxia via an HIF-1α mechanism. Endogenous renalase shows potential as a therapeutic agent for the prevention and treatment of AKI.