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 selection bias.
The unit of randomization in this study is individual; that is, each patient will be independently and separately assigned to one of the groups.
The randomization tool used is the Sequence Generator available on the website www.random.org. In this tool, a random sequence of numbers from 1 to 15 is generated and 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 the group assignment of the patients. For example, if number 7 appears in the column for Group C, the seventh eligible patient will be assigned to Group C.
This process will be repeated for every set of 15 patients. That is, after completing the allocation for the first 15 patients, a new random sequence will be generated for the next 15 patients. This process will continue until the desired sample size is reached.
Allocation concealment will be ensured through the use of opaque, sealed, and sequentially numbered envelopes. The generated randomization sequence will be kept confidential within these envelopes. Each envelope will be opened only after confirming the patient's eligibility and obtaining written informed consent. The envelopes will be prepared and maintained by an independent researcher who is not involved in patient recruitment or data collection, in order to prevent any potential allocation bias.
In this study, to minimize bias and enhance the accuracy of outcome measurement, blinding will be implemented comprehensively and at multiple levels. The following individuals will remain blinded to the group allocation of patients throughout the study process:
Participants (Patients):
All patients enrolled in the study will be unaware of the type of drug administered and their respective treatment group. Additionally, they will not be informed about the allocation of other participants to different groups. It is important to emphasize that all patients will sign a written informed consent form prior to participation and will be fully aware of their involvement in a clinical trial. Therefore, the blinding process will in no way violate ethical principles and will be conducted in full accordance with ethical guidelines.
Medical Personnel (Physicians, Anesthesiologists, Surgeons, and Nurses):
The study drugs for all groups will be prepared in advance by the principal investigator in identical, unlabeled syringes. These syringes will be delivered to a nursing staff member who has no knowledge of the group allocation or the nature of the drugs. A fully independent anesthesiologist, who is not involved in any part of the study design, implementation, or data analysis and is completely blinded to the type of drug administered and the treatment group of the patients, will be responsible for performing the intrathecal injection.
Researchers and Study Team:
Researchers responsible for data collection, documentation, and patient follow-up—including anesthesia residents—will be blinded to the type of drug administered and the patients' treatment groups. These individuals will not be involved in the study design, patient allocation, or drug administration, and their role will be limited to recording the outcomes.
Outcome Assessors:
All assessments of primary and secondary outcomes will be conducted by individuals who are blinded to the treatment groups. These assessors will have no knowledge of the specific interventions received by the patients and will document outcomes solely based on predefined criteria.
Data Analysts:
Statistical analysis of the data will be performed by an individual who has access only to the group codes (A, B, C) but is unaware of the actual interventions corresponding to each group. Final unblinding will occur only after the completion of the statistical analysis and confirmation of the results.
Manuscript Authors:
The authors responsible for drafting the manuscript will also remain blinded to the group allocation until the final stage of data analysis and unblinding. This measure is intended to preserve objectivity in the interpretation of the findings.