A total of 108 patients with the study inclusion criteria were randomly assigned to three groups of 36 patients, including Budesonide nasal spray as the standard treatment in comparison with two intervention groups of Betamethasone nasal drop, and Budesonide nebulizing suspension. To begin with, one of the letters A, B, C is considered for each treatment, and Random Allocation software is used to build random blocks. The software generates 18 different blocks with size 6, according to the total sample size of 108, the blocks size of 6, and considering 3 treatment groups.
There are 6 blanks in each block in which the 3 letters A, B, and C are randomly combined in different sequences, assuming that each letter is repeated twice in each block. Thus, the software output is a list of 18 blocks, each of which has 6 blanks, which are filled with different sequences of A, B, and C (each letter is repeated twice in every single block). In other words, we have a total of 18 blocks, each of which has 2 locations for every study treatment. Finally, by completing the sampling, we reach 36 patients in each of groups A, B and, C.
Next, each block is placed in separate envelopes, encoded from 1 to 18. To maintain the principles of allocation concealment, the physician is not aware of the sequence inside each envelope. The envelopes are given to someone outside the research team who informs the physician about assigning each patient to treatment groups during the study.