Sample size
infection
INFECTION
The sample size for NINJA was based on observed infection rates in previous studies and on the cosmetic outcome in the NINJA-P study. The sample size of 416 was based on a clinically important difference of 7 per cent in the proportion of patients with an SSI between the two treatment groups, as well as a 15 per cent difference between treatment groups in the proportion of those achieving an optimal result in terms of the cosmetic appearance of the nail. These differences were chosen to provide 90 per cent power at a two-sided 5 per cent level of significance, with no adjustment made for multiple comparisons.