“…8,14,15,17,18,22,23,25,41,42 This partially could be the result of considerably lower ICC values during rest (fair-to-moderate) compared with the procedures (moderate-to-almost perfect), which was contrary to several previous studies. 8,10,[21][22][23]26,43 ICC values are assumed to be susceptible to between-subject variability, and a lack of subject variability can cause incorrect low ICC values. 34,44 A minority of the validation studies have assessed only patients after cardiac surgery, which likely were more homogenous populations in terms of diagnosis, age, severity of illness, pain and level of sedation, and analgesia than that of a general ICU population or a mixed medical/ surgical population.…”