Sample size and statistical analysis To demonstrate equivalence in efficacy of the two treatment groups, initially, the sample size was set at 250 patients in each study group based on an expected cure rate of 85% in the IV group and acceptance of a 75% cure rate in the switch group. (=0.05, 2 sided; 1-=0.80). The absolute difference in cure rate including 95% CI was calculated. Equivalence was rejected if the lower limit of the CI exceeded -10%. Eventually, with less than anticipated enrolment, a 15% lower effectiveness in the intervention group could be excluded with =0.05 and 1-=0.80.