RELACS

Why is this trial needed?

Chronic subdural hematoma (CSDH) is the most common emergency neurosurgical procedure, primarily driven by an aging population and the widespread use of antithrombotic medications. A significant clinical challenge arises in the approximately 20–25% of CSDH patients who require oral anticoagulation (OAC) for atrial fibrillation (AF).

Postoperatively, neurosurgeons face a critical dilemma:

• Withholding OAC exposes patients to a high and immediate risk of devastating thromboembolic events, such as ischemic stroke.
• Resuming OAC carries a perceived risk of hemorrhagic complications, including acute intracranial hemorrhage and hematoma recurrence requiring reoperation

This uncertainty is compounded by a complete lack of evidence, leading to wide variations in clinical practice. The RELACS trial was designed to resolve this critical evidence gap.

What is the primary objective of the RELACS trial?

The aim of the RELACS trial is to determine the net clinical effect of early versus late postoperative resumption of oral anticoagulation in CSDH patients with AF.

RELACS is a Phase III, international, multicenter, superiority, assessor-blinded randomized controlled trial. Eligible patients are randomized 1:1 to one of two arms:

• Early Resumption (Intervention): OAC resumed 5 days post-surgery.
• Late Resumption (Control): OAC resumed 30 days post-surgery.

The primary outcome is a composite of thromboembolic events (e.g., ischemic stroke), hemorrhagic events (e.g., intracranial hemorrhage), and vascular death within 90 days. We hypothesize that early resumption will be superior, reducing thromboembolic complications and vascular death without a significant increase in hemorrhagic risk.

Where are we now?

Recruitment for RELACS officially began in July 2025. The trial is coordinated by Helsinki University Hospital and is a major collaborative effort, enrolling patients across all five university neurosurgical centers in Finland, Karolinska University Hospital in Sweden and FICEBO.

The target sample size is 332 patients, and recruitment is expected to take ca. 2 years. With the protocol now published, the trial is actively underway to provide definitive, high-quality evidence to guide this crucial and common clinical decision.

The trial protocol was published in Trials in 2025 and is available here.

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HUS: Jarno Satopää, Pihla Tommiska, Miikka Korja, Mika Niemelä and others

TAYS: Teemu Luoto, Minna Rauhala and others

TYKS: Jussi Posti, Dan Laukka and others

KYS: Nils Danner, Ville Leinonen and others

OYS: Oula A. Knuutinen, Tommi Korhonen, Sami Tetri and others

Karolinska: Jiri Bartek, Alexander Flethcer-Sandersjöö, Bjartur Saemundsson and others

FICEBO: Teppo LN Järvinen, Simo Taimela

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