Anticoagulation during CKRT reduces dialysis, death in AKI patients

Use of anticoagulants during continuous kidney replacement therapy (CKRT) helps lower dialysis dependence and prevent death at 90 days among critically ill patients with acute kidney injury (AKI) following admission to the intensive care unit (ICU), a study in Singapore has shown.

Such association is statistically significant for regional citrate anticoagulation (RCA) and shows a trend toward the same benefit for systemic heparin anticoagulation, according to the researchers, noting that anticoagulation must be considered during CKRT whenever possible.

In this retrospective observational study, the first CKRT session was assessed in critically ill adults with AKI in Singapore from April to September 2017. A composite of dialysis dependence or death within 90 days of ICU admission was the primary outcome. Use of anticoagulation (ie, RCA or systemic heparin) was the main exposure variable.

The researchers performed multivariable logistic regression to adjust for possible confounders, such as age, female sex, Acute Physiology and Chronic Health Evaluation (APACHE II) score, liver dysfunction, coagulopathy (international normalized ratio [INR] >1.5), and platelet count <100,000/μL.

A total of 276 patients from 14 adult ICUs were included. Of these, 176 (63.8 percent) had dialysis dependence or death within 90 days of ICU admission (19 dialysis dependence and 157 deaths). [Ann Acad Med Singap 2023;52:390-397]

Anticoagulation use was associated with a significant decrease in the likelihood of dialysis or death (adjusted odds ratio [aOR], 0.47, 95 percent confidence interval [CI], 0.27‒0.83; p=0.009).

Multivariate analysis using anticoagulation as a three-level indicator variable revealed the association of RCA with mortality reduction (aOR, 0.46, 95 percent CI, 0.25‒0.83; p=0.011), with heparin showing a consistent trend (aOR, 0.51, 95 percent CI, 0.23‒1.14; p=0.102).

“Comparing patients who had anticoagulation during KRT against those who did not, there were more patients in the group that did not receive anticoagulation with platelet counts <100,000/μL,” the researchers said. “This could be a biomarker for bleeding risk.”

However, the association between anticoagulation use and the primary outcome persisted after adjustments during multivariable analysis.

“There were differences in the prescribers who chose anticoagulation and those who omitted anticoagulation, but this may just reflect anticoagulation preference rather than expertise with renal care,” the researchers said. “We therefore did not adjust for it in multivariable analysis.”

Critically ill patients

Ideally, CKRT is prescribed with anticoagulation to prolong filter lifespan because problems with filter clotting lead to disruptions to the procedure and may induce blood loss. However, this is often contraindicated in critically ill patients due to bleeding diathesis, recent surgery precluding heparin use, or liver failure precluding RCA use, which will result in metabolic acidosis and reduced ionized calcium.

Additionally, disease-induced coagulopathy or thrombocytopenia may also make anticoagulation unnecessary in severely critically ill patients, according to the researchers.

In Singapore, continuous veno-venous hemodiafiltration is the most common mode of CKRT, which is consistent with other studies because of its lower failure rate compared with other modalities. [BMC Nephrol 2017;18:69; Ann Acad Med Singap 2020;49:306-311]