4.10. Sample size
Based on data from the COPE-II study (exacerbation
rate (days/patient/year) intervention group: 0.116; baseline (control group): 0.176), both with an estimated SD of 0.17 and allowing for over dispersion, 105 patients per group are needed to provide 80% power to detect an effect of this size. Allowing for an attrition rate of 30% in these severe patients with comorbidities and a possible potential reduced
effect in this group of patients compared to the COPE-II population, 150 patients per study group will be included.