Active subperiosteal vs. passive subdural 24-h drainage following single burr hole evacuation of chronic subdural hematoma: statistical analysis plan for the multicenter, randomized, non-inferiority clinical trial SUPERDURA

BACKGROUND: In Denmark, the current treatment of patients with symptomatic chronic subdural hematoma (CSDH) is single burr hole hematoma evacuation followed by 24-h passive subdural drainage. However, recent studies indicate that 24-h active subperiosteal drainage may be safer and have fewer recurrences. The upcoming SUPERDURA trial will investigate 24-h active subperiosteal drainage versus 24-h passive subdural drainage following single burr-hole evacuation of symptomatic CSDH. This study presents the statistical analysis plan for the SUPERDURA trial.

METHODS: SUPERDURA is a national multi-center non-inferiority randomized clinical trial. The primary outcome is a composite of 90-day mortality and ipsilateral recurrent CSDH requiring reoperation within the 90-day observation period. Secondary outcomes are 90-day simplified modified Rankin Scale questionnaire (smRSq) score, complications related to surgery, postoperative serious adverse events during the admission and at 90 days, and length of hospitalization. Exploratory outcomes are smRSq score as an ordinal outcome, each component of the primary outcome, and discharge destination. A total of 354 participants must be included (177 in each intervention group) in the study to achieve a stable power > 90% with an alpha of 5% for non-inferiority testing of the primary composite outcome with a margin at 7% absolute risk increase. The allocation sequence and block sizes are blinded to the investigators. Interim analyses for safety and efficacy/futility will be performed after follow-up is completed for 120 and 240 participants, respectively. A Data Safety Monitoring Committee charter has been created following published recommendations. Final analysis will be done by two statisticians blinded to the intervention, creating two abstracts that are unblinded once approved by the study steering committee.

DISCUSSION: The proposed analysis plan is designed in accordance with current guidelines, has clinically important primary and secondary outcomes, and was submitted before the inclusion of the first participant in the SUPERDURA trial to limit bias and increase study transparency and reproducibility.

TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT06621407.