Table 11 Estimates from segmented linear regression for adverse events in Site 4

 Intercept

29.69 (26.89, 32.49)

 Pre-intervention trend

−0.10 (−0.40, 0.21)

0.55

There was no apparent significant trend in the overall adverse event rate.

 Change in slope (implementation phase vs pre-intervention phase)

−0.64 (−1.15, − 0.13)

0.02

There was a significant deviation in the event rate during the implementation phase which probably represents a real clinical impact.

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

1.57 (−4.05, 7.18)

0.59

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

0.32 (−0.29, 0.93)

0.31

This trend was maintained but was not significantly different from the implementation phase.

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

0.32 (−0.29, 0.93)

0.31