Table 6– A comparison of the numbers needed in a cross-over study design when data from 1 day, the mean of 3 days or the mean of 5 days are used for calculations in α1-antitrypsin deficiency (A1ATD) and usual chronic obstructive pulmonary disease (COPD)
DaysIL-8MPOLTB4NeutrophilMacrophage
A1ATDCOPDA1ATDCOPDA1ATDCOPDA1ATDCOPDA1ATDCOPD
1318333980186653267832
347386443254914
546269543143810
  • Data are presented as the numbers required to provide an 80% chance of detecting a 50% decrease in mediators or cells at the 5% level of significance. Power calculations were performed for each mediator or cell using data from the first study visit for 1 day data. Power calculations were performed using data collected on the first 3 days (visit 1 to 3) or the first 5 days for 3 and 5 day data, respectively. IL: interleukin; MPO: myeloperoxidase; LTB4: leukotriene B4.