Sample size calculation for this analysis of repeated measures to detect an effect size of 0.2 at 80% power and a 0.05 significance level indicated that a sample size of 68 patients is needed (according to G- POWER 3.1 analytical software, Franz Faul, Universitat Kiel, Germany). A sample of at least 89 participants for both groups combined was required on the basis of these parameters, allowing for a 30% attrition rate.