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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Early dialysis does not improve survival among critically ill patients with acute kidney injury, new research shows. A large multinational trial found that starting dialysis within 12 hours of acute kidney injury was no more effective than watchful waiting with delayed dialysis.

Acute kidney injury means that the kidneys stop working suddenly. It is a common complication in patients in intensive care units. If acute kidney injury is not treated, abnormal levels of salts and chemicals can build up in the body, and this can be fatal.

The usual treatment is dialysis or renal replacement therapy, in which a machine removes waste products from the blood. But there is longstanding debate about the best time to start this treatment.

The STARRT-AKI trial included more than 3000 patients in intensive care who developed acute kidney injury. It compared the two strategies: early dialysis or delayed dialysis with watchful waiting. Researchers found that rates of death were similar, regardless of strategy. But among those who survived for at least 90 days, more patients who received early dialysis needed ongoing dialysis. This suggests early dialysis might disrupt or delay the recovery of kidneys.

More research is still needed into the optimum time to start dialysis in these critically ill patients.

What’s the issue?

Acute kidney injury is a common complication for patients in intensive care. Many will need dialysis in which a machine filters the blood, acting in a similar way to a healthy kidney.

There is long-standing uncertainty about the best time to start dialysis in these patients. Patients need immediate dialysis if they have metabolic conditions such as excessive blood levels of potassium (hyperkalaemia), acid (metabolic acidosis) or waste products like urea (uraemia). But for patients without these complications, doctors do not know what the benefits or dangers of early dialysis are.

Dialysis can prevent life-threatening complications associated with acute kidney injury. However, starting dialysis early might be unnecessary in some patients and could cause further damage to the kidneys. Dialysis is also an expensive treatment.

Previous studies comparing early and delayed strategies for starting dialysis had conflicting findings. A multinational clinical trial was needed to provide clarity.

What’s new?

The STARRT-AKI trial (Standard versus Accelerated Initiation of Renal-Replacement Therapy in Acute Kidney Injury) is the largest international study of its kind. It was conducted from October 2015 to September 2019 and involved 168 hospitals in 15 countries.

A total of 3019 critically ill patients with severe acute kidney injury were assigned to one of two treatment strategies. In the early treatment group, dialysis was started almost immediately after the patient was deemed eligible. In the standard treatment group, the patient was observed, and dialysis started only if necessary. That was if complications arose, the kidney injury persisted for more than three days or at the clinicians’ discretion. Dialysis was not always started for those in the standard strategy.

The study found that, after 90 days:

  • similar numbers in both groups had died: 43.9% patients in the early treatment group, 43.7% patients in the standard treatment group
  • among surviving patients, more in the early treatment group needed to continue with dialysis (10.4%) than in the standard treatment group (6%)
  • among surviving patients, more in the early treatment group had adverse events (23%), mostly related to acute dialysis therapy, than in the standard treatment group (16.5%).

This means that early dialysis did not reduce the risk of death at 90 days compared to standard treatment. Adverse events were more frequent with early treatment, and long term kidney recovery outcomes were worse.

Why is this important?

This research suggests critically ill patients with acute kidney injury do not benefit from starting dialysis earlier than normal. Early dialysis did not improve survival. In addition, more patients who received early treatment needed to continue dialysis after 90 days. They had more adverse events than patients in the standard treatment group. This suggests giving dialysis too early might impair or delay the kidney from recovering and lead to longer term need for dialysis therapy.

What’s next?

The study found early dialysis does not improve survival in critically ill patients with acute kidney injury. But delaying dialysis too long can also be potentially dangerous. More research is still needed on how long is too long to wait before treating this group of patients.

The team behind STARRT-AKI intends to use the large amounts of data generated in this trial to explore how different factors (such as sex, age and severity of illness) affect the chances of survival and recovery from acute kidney injury.

You may be interested to read

The full paper: The STARRT-AKI Investigators. Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury. New England Journal of Medicine. 2020;383:240-51

A study looking at the likelihood of critically ill patients experiencing acute kidney injury: Hoste EA, and others. Epidemiology of acute kidney injury in critically ill patients: the multinational AKI-EPI study. Intensive Care Med. 2015;41:1411-1423


Funding: This study was funded by the Canadian Institutes of Health Research, the NIHR's Health Technology Assessment Programme, Baxter Healthcare, the National Health Medical Research Council of Australia and the Health Research Council of New Zealand.

Conflicts of Interest: Some of the authors have received fees from pharmaceutical companies.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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