**3.4 Conclusion regarding the ETM based analysis**

The different approaches in Section 3 led to the sasimilar conclusions that there is a difference in the way good trackers and poor trackers transition between states. Most

*Modelling Agitation-Sedation (A-S) in ICU: An Empirical Transition and Time to Event… DOI: http://dx.doi.org/10.5772/intechopen.105480*


**Table 10.**

*Departure state j = 2 summed over all time points k, k = 2, … ,10.*


#### **Table 11.**

*Computation of Commenges' test for the WPB strata [9].*


#### **Table 12.**

*Computation of Commenges' test for the remaining A-S studies.*

of this difference occurs in states 0 and states 2, as defined. Good trackers tend to have higher probability of transitioning into state 0 than poor trackers, and good trackers tend to have lower probability of transitioning into state 2 than poor trackers, noting that state 2 indicates more violations are occurring, and state 0 indicates fewer violations. The probability of transitioning into state 2 overall appears to increase as ICU time increases. This is most likely due to the fact that poor tracking patients have longer ICU times, and so, as time goes on, it is only the poor trackers' transitions that are being estimated.

By categorising patients according to their total ICU time (≤64, >64) similar trends were found. The Commenges' test established a statistically significant difference between the two tracking strata (p = 0.007), and that this difference was mainly due to transitions out of states 0 and 2. For the tracking metric of Chase et al. [14], the Commenges test demonstrated a statistically significant difference between the two good versus poor strata (p = 0.019), with this difference mainly due to transitions out of states 0 and 1. Overall, the WCORR [10] and Rudge [11] classifications of tracking/ strata, the transision probability profiles for the 3 state process, good and poor trackers are not significantly different, but exhibited some difference mainly due to transitions out of state 2.

**Figure 12.** *Probability of being in each state as time progresses given start state 0. Top is good trackers; bottom is poor trackers: WCORR of [10].*
