Randomization and Blinding
BLIND
A total of 600 opaque envelopes (200 for each site, block randomized 1:1) with sequential study numbers containing randomly assigned irrigation fluid temperatures were prepared by an independent statistician. The envelopes were kept sealed at each site until the included patient was draped in the operation room. The envelope was opened by the neurosurgeon performing the cSDH surgery. It was not possible to blind the treating surgeon to the treatment allocation. To minimize bias, the patient was not informed of treatment allocation, and the treatment allocation was not recorded in the medical records as this could bias the indication for reoperation. An independent statistician decoded the individual treatment allocations first at the completion of the study, thus making sure that the investigator performing the final statistical analyses was blinded to treatment allocation until the statistical analyses were completed.