Sample size calculation
We used the mean and standard deviation from pilot study (mean and standard deviation: 2.3 and 0.57). In a two-tailed analysis where α = 0.05 and β = 80%, 24.1 patients were required to obtain a 20% difference of the mean between the experimental and control groups. A total of 54 patients were required to maintain acceptable statistical power, assuming a 10% dropout rate. Sample Size Software, 3rd edition from Sample Size Tables for Clinical studies by David Machin, Michael Campbell, Say-Beng Tan et al. was used for calculation.