Sample size estimation
This was a non-inferiority trial. The definition of non-inferiority margin was 1.3 and the desirable significant level α was 5%. The value of Power 1-β was 80%. The main treatment effect was measured by the VAS difference at days 1 and 8. We expected decreases from 8 points to 4.5 points in the treatment group and from 8 points to 3.2 points in the control group after treatment. The standard deviation was 1.5. The random allocation rate was 1 to 1 and the expected dropout rate was 20%. Finally, a sample size of 40 participants with complete data was required.