The main treatment of chronic subdural haematoma (CSDH) is neurosurgical evacuation with subsequent drainage. However, consensus on optimal drain modality and placement is lacking.

To examine whether 24-hour active subperiosteal drainage is non-inferior to 24-hour passive subdural drainage after a single burr hole evacuation of a symptomatic CSDH.

SUPERDURA is a multicentre randomised non-inferiority trial encompassing all neurosurgical units in Denmark. Adult patients with symptomatic CSDH admitted to a Danish neurosurgical unit for single burr hole evacuation will be screened for inclusion. Patients who are not able to give informed consent, and patients with recurrent CSDH, known cerebrospinal fluid abnormalities and other known brain pathologies will be excluded. Patients with bilateral CSDH will be registered as one case and treated similarly on both sides. Before surgical haematoma evacuation, patients will be randomised to 24-hour passive subdural drainage or 24-hour active subperiosteal drainage. The patients included and the two study statisticians will be blinded. The primary outcome is a composite outcome of 90-day mortality and symptomatic CSDH recurrence. Secondary outcomes are 90-day simplified modified Rankin score, 90-day serious adverse events and complications related to surgery or occurring during admission, including intracerebral haemorrhage due to misplaced drains, acute subdural haematoma, tension pneumocephalus, wound infection, drain seepage, subperiosteal haematoma, thromboembolic events, infections and seizures.

A detailed statistical analysis plan is published separately. Sample size simulations of non-inferiority with a threshold of 7% increased relative risk show that a total of 354 participants will be required to demonstrate a relative risk reduction of recurrent CSDH and mortality of 30% for the cohort receiving active subperiosteal drainage given a stable power above 80% with an alpha of 5%. The study inclusion period is estimated to last 2 years.

Ethics approval for the inclusion of competent patients has been obtained from the North Denmark Region Committee on Health Research Ethics. Results of the primary and secondary outcomes will be submitted for publication in an international peer-reviewed journal and presented at relevant neurosurgical meetings.

N-20240009, accepted 13 May 2024 and 13 December 2024.

NCT06621407.