In this study, simple randomization will be used to allocate participants into three groups (Group A, Group B, and Group C). This method ensures that each eligible patient has an equal and independent chance of being assigned to any of the groups, thereby minimizing the risk of selection bias.
In this trial, the unit of randomization is individual; meaning that each patient will be assigned to one of the groups independently and separately.
To generate the random sequence, the Sequence Generator tool available on the website random.org will be used. This tool creates a random sequence of numbers from 1 to 15, which will be equally distributed among the three groups A, B, and C. Each number from 1 to 15 is assigned to one of the groups, and the order of these numbers in the list determines how patients are allocated. For example, if number 7 is assigned to Group C, the seventh eligible patient will be placed in Group C.
This process will be repeated for every set of 15 patients. That is, after the first 15 patients are allocated, a new random sequence will be generated for the next 15 patients. This procedure will continue until the desired sample size is reached.
To ensure allocation concealment, opaque, sealed, and sequentially numbered envelopes will be used. The generated random sequence will be placed confidentially inside these envelopes. Each envelope will only be opened after confirming the patient's eligibility and obtaining written informed consent.
The preparation and safekeeping of these envelopes will be carried out by an independent researcher who is not involved in patient recruitment or data collection, in order to prevent any allocation bias.
In order to minimize bias and enhance the accuracy of outcome measurements, a comprehensive, multi-level blinding strategy will be implemented in this study. The following groups will remain blinded to the treatment allocation of participants throughout the study:
Participants (Patients):
All patients enrolled in the study will be unaware of the type of drug administered and the treatment group to which they have been assigned. Additionally, they will not be informed about the group allocation of other participants. It is important to note that all patients will sign a written informed consent form prior to enrollment and will be aware of their participation in a clinical trial. Therefore, the blinding process will be conducted in full compliance with ethical principles and does not conflict with any ethical considerations.
Healthcare Personnel (Physicians, Anesthesiologists, Surgeons, and Nurses):
The study drugs for each group will be prepared in advance by the principal investigator and placed in identical, unlabeled packages. These packages will be delivered to nursing staff who have no knowledge of the drug contents or the method of patient allocation. A separate, independent anesthesiologist—who is not involved in any phase of the study design, implementation, or data analysis and is fully blinded to the type of drug and treatment groups—will be responsible for administering the intrathecal injection.
Researchers and Study Team Members:
Individuals responsible for data collection, documentation, and patient follow-up—including anesthesia residents—will remain blinded to the type of drug administered and the treatment group. These individuals will not be involved in protocol design, patient allocation, or drug administration, and their sole responsibility will be to record the study outcomes.
Outcome Assessors:
All assessments of primary and secondary outcomes will be carried out by individuals who are blinded to the patients’ treatment groups. These assessors will have no knowledge of the interventions received by the patients and will record outcomes strictly based on predefined criteria.
Data Analysts:
Statistical analysis of the data will be performed by an individual who only has access to group codes (A, B, C) and is unaware of the actual interventions corresponding to each group. Final unblinding will occur only after the completion of all statistical analyses and the final confirmation of results.
Manuscript Authors:
The authors responsible for drafting the manuscript will also remain blinded to group allocation until the final stage of data analysis and unblinding. This measure is taken to preserve objectivity in the interpretation of the study findings.