uncorrected rate ratio

After implementation of the checklist, the total number of complications decreased from 27.3... to 16.7 per 100 patients ..., corresponding to an absolute reduction of 10.6 complications ... and to an uncorrected rate ratio of 0.613..." Where does this 0.613 come from? What do they mean by "uncorrected'?

I calculate once and round up number is 0.612
Plus I found no where to explain what is uncorrected