Statistics
Continuous data were visually inspected for normal distribution in histograms and QQ-plots. For analysing the primary outcome and other repeated measures a generalized linear mixed model with unstructured covariance was used, and results were presented with 95% c.i. Missing data were assumed to be missing completely at random and handled by maximum likelihood estimation within the linear mixed model. No specific per protocol measure of adherence or compliance was defined and all patients undergoing elective surgery were included in the analysis. In other comparisons between groups a 