y 4--5 minutes of boarding increased the length of stay of other patients by one minute. PIT did not mitigate this effect.

How does this improve population health?

PIT improves the efficiency of ED care but does not attenuate the effect of hospital boarding. Improved hospital throughput is needed to reduce the consequences of boarding.

Operational Metrics Before and After Implementation of the PIT
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Implementation of PIT was associated with significantly shorter median LOSD at both EDs ([Table 2](#t2-wjem-21-647){ref-type="table"}), with a decrease of 5.9% (19 minutes) at the AED and 3.3% (8 minutes at CED). After implementation of the PIT model, we found a statistically significant decrease in D2P time at both sites, and a statistically significant increase in boarding time. D2P times demonstrated the largest shift after implementation of PIT. The median D2P time decreased by 22 minutes or 43%. The D2P was 51 minutes (IQR 37--68) pre-PIT as compared with 29 minutes post-PIT (IQR 21--41) at the AED (p \< 0.01). At the CED, the D2P went from 58 minutes (IQR 38--77) to 40 (IQR 26--59), a 31% decrease (p\<0.01). Post-PIT implementation median active-care time increased by 5 minutes or 1.8% at the AED (pre-PIT median time = 264 \[IQR 249--282\] post-PIT = 269 \[IQR 251--290\], p = 0.01), and 9 minutes or 5% at the CED (pre-PIT median time = 180 \[IQR 170--192\] post-PIT = 189 \[IQR 175--205\], p \< 0.01). For both EDs, median A2D significantly increased (AED Δ = 13.5 minutes \[95% CI: 8.1, 18.01\]), p \< 0.01; CED Δ = 29 minutes \[95% CI: 24.2, 34.8\], p \< 0.01), with the increase in median A2D significantly larger at the CED (p \< 0.01).

A series of quartile regressions were performed to determine the effects of PIT implementation and boarding time on operational metrics at both sites, as can be seen in [Table 3](#t3-wjem-21-647){ref-type="table"}. In both EDs, after adjusting for variability in overall median ED census (centered on the median pati