Figure 3.

Balance of surveillance cost versus savings from reductions of 10%, 20% and 30% per surveillance period for surveillance strategies of one quarter a year, two quarters a year and continuous surveillance for starting surgical site infection (SSI) risk of 10%. Model assumes that reductions in infection risk are achieved in conjunction with improvement programmes during surveillance periods and maintained between each surveillance period. No further reductions in risk of infection were included in the model once a postulated minimum SSI risk of 3% was reached.