The group allocation will be performed through permuted block randomization at an assignment ratio of 1:1. For allocation concealment, the randomization codes will be kept in opaque, sealed, sequentially numbered envelopes.
Sample size is estimated at 50, however, to take account of potential withdrawals, 56 patients (n=28 per group) will be recruited for the study. First, create and seal 28 treatment A envelopes and 28 treatment B envelopes. To create a block of 4, we will select 2 treatment A envelopes and 2 treatment B envelopes. We will shuffle these 4 envelopes thoroughly, and place this block of 4 in a separate pile. Then, we will prepare additional blocks of 4 until all 28 treatment A and B envelopes have been used. All additional blocks will be placed in their own individual piles. We will have 14 individual piles of shuffled blocks of 4, for example AABB, BBAA, ABBA, BAAB, ABAB, BABA.