2.3 Randomization
The study was designed as a randomized, double-blind, parallel-group controlled trial. The eligible children were randomized into two groups after enrolment into the study: Intervention (I) and control (C) group. Computer-generated block randomization with variable block sizes was employed. The person responsible for the preparation and labelling of study drug vials was not involved in enrolling the subjects, administering the intervention, or analyzing the data. Each enrolled patient was administered the drug from the next serially labelled vial, corresponding to the sequence of his/her enrolment. The ketamine and placebo mouthwash preparations were identical in appearance, taste, and smell. The labelling on the drug vial mentioned only the serial number, and the serial number’s randomization sequence was not revealed to the principal investigator. Thus, both the patient and the principal investigator were masked to the assigned group. After the completion of enrolment, the analyst was provided with the randomization list mentioning groups “A” and “B” without revealing the actual ketamine and placebo groups. The statistical analysis was hence done without the knowledge of the study arms (triple-blind). The actual study arms were disclosed after all enrolment and statistical analyses were completed. Allocation concealment was ensured by randomization of the patients coupled with using identical intervention and control vials.