Table 10 Estimate from segmented linear regression for adverse events in Site 3

 Intercept

3.27 (2.12, 4.42)

 Pre-intervention trend

0.04 (−0.06, 0.15)

0.42

There is a trend towards increasing event rates although this is not significant.

 Change in slope (implementation period vs. pre-intervention period)

0.01 (−0.16, 0.18)

0.92

The event rate doesn’t change but given the wide confidence intervals it is difficult to be precise about whether this is a true effect.

 Immediate change in level (implementation period vs. pre-intervention period)

0.21 (−1.55, 1.97)

0.81

 Change in slope (post-intervention period vs implementation period)

−0.27 (− 0.47, − 0.07)

0.01

The trend significantly reduced over this period (although the overall number of events per patients day increases)

 Immediate change in level (post-intervention period vs. implementation period)

1.98 (−0.22, 4.18)

0.09