<qa>  What is the lowest relevant difference in effect?Sample size. The study population is calculated on the basis on LOS for patients undergoing cystectomy at the Department of Urology, Aarhus University Hospital, Skejby in 2008. Average LOS was 13 days with a standard deviation of 4.75 days. Risk of type 1 error was 5 at a 2-sided analysis and strength at 80. Lowest relevant difference in effect is a 20 reduction in LOS in the intervention group. When a 2-sided comparison is made, 92 patients have to be included; 46 in the intervention and control group, respectively.Written information about the study is forwarded to the patients along with the appointment for a uro-oncological evaluation. 