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.