Sample size calculation
pain
The sample size calculation for this study was based on an alpha (α) value of 0.05 and power of 0.80, with p-values of 0.2 and 0.05 assumed for p-value one and p-value two, respectively, for chronic postsurgical pain at 6, 24 hours, three, six, and twelve months [CONSORT 2010 Flow diagram