Response to Monstrey et al. ‘Evaluation of the antiseptic activity of 5% alcoholic povidone-iodine solution using four different modes of application: a randomized open-label study’

We were interested in the publication by Monstrey et al. because we have conducted a similar work named TApAS which does not lead to the same conclusions despite a larger study population [ [1], [2]]. Those two randomized single-centre studies compared the reduction in the number of micro-organisms (aerobic and anaerobic) on healthy skin (N = 132 for the TApAS study and modified intention-to-treat (mITT) NmITT = 32 and per protocol (PP) NPP = 27 for Monstrey et al.'s study) using two application techniques of 5% alcoholic povidone-iodine (PVP-I): back-and-forth friction versus concentric circle. Our study found no significant difference whatever the technique of application whereas Monstrey et al. concluded in favour of the back-and-forth friction. What can explain these differences?