New Insights on Acute Kidney Injury Patient Survival in the ICU: Greater CRRT Use May Tip the Balance

Few specialties are as complex, demanding, or defined by such urgent patient needs as intensive care medicine. It’s this combination that draws many of us, myself included, to the field. 

As a nephrologist and intensivist, one of the most compelling challenges is improving outcomes for critically ill patients with acute kidney injury (AKI), a group in which outcomes can be poor.

AKI can affect more than half of patients in the ICU.¹ Of those who require renal replacement therapy (RRT), around 40% do not survive.^2,3 It’s a statistic that troubles many of us who work in this setting. 

The main RRT modalities available to clinicians – continuous renal replacement therapy (CRRT) and intermittent hemodialysis (IHD) – have been well studied. But, in terms of survival benefit, robust data showing superiority of one over the other have been largely absent. Part of the explanation for this is that, in practice, the best choice depends on the patient’s situation.

Important gaps in our understanding of how to improve outcomes remain. And as technology and our ability to intervene have advanced, they’ve added new layers of complexity to decision-making.

But, as with anything complex, practice leads to progress. In other high-risk treatments, such as mechanical ventilation, surgery, and dialysis for end-stage renal disease, there’s a well-established link between the frequency of procedure utilization and improved outcomes.^4–6  We wondered if this was also true for CRRT. 

Specifically, we wanted to see whether the frequency of CRRT utilization as a proportion of all acute RRT in an ICU affects patient outcomes. And whether greater use of CRRT is linked with better survival, regardless of a hospital’s size, setting, or patient mix.

I’m pleased to say our study and its findings have been published in Intensive Care Medicine. Indeed, our findings suggest the more frequently hospitals use CRRT, the better the survival outcomes for those patients who require acute RRT.

As far as we know, this is the first time this particular question has been explored on such a scale. Using the Premier Incorporated AI database, we analyzed data from 50,000 critically ill ICU patients in 426 hospitals across the US. All patients received acute RRT in hospitals offering both CRRT and IHD and were still hospitalized three days later. We split hospitals into quartiles based on how often they used CRRT for their patients who needed acute RRT in the ICU and assessed hospital outcomes censored at 90 days.

We found a clear dose-response relationship – as hospital-level CRRT use increased, so did patient-level survival. Compared with the lowest-use hospitals, mortality was 6% lower in the third quartile and 15% lower in the highest quartile. This finding was consistent across multiple sensitivity analyses. 

These findings aren’t just statistically significant – they are also clinically meaningful and, quite simply, translate into lives saved. 

We’ve developed several hypotheses about why this might be occurring, which have implications for clinical practice. 

While this wasn’t a direct comparison of CRRT and IHD, CRRT may have advantages over IHD in appropriate patients – for example, those who are hemodynamically unstable or need precise fluid management. However, the improved survival seen in hospitals with higher CRRT use likely reflects more than just the therapy alone.

Our findings suggest that these hospitals may have developed more effective ways to care for these critically ill patients. This could be due to better training, greater clinical expertise, earlier recognition of disease progression, more coordinated care, or stronger communication and workflow systems.

Now that we have this important starting point, the clinical community can build on it through further research and continue to improve outcomes. Inch by inch, study by study, we can continue to deliver the promise that inspired so many of us to enter intensive care medicine in the first place: helping patients survive – and recover – even in the most complex and critical moments.