Introduction:
Pain in the critically ill affects nearly 50% of patients. In patients unable to self-report pain, behavioural scales are used. The aim of this study was to validate the Polish version of the Critical Care Pain Observation Tool (CPOT).

Material and methods:
The prospective observational cohort study included patients observed during non-nociceptive and nociceptive procedures, at rest, during the intervention, and 15 min after each intervention. Assessments included self-report by patients and CPOT assessment carried out by two blinded observers.

Results:
A total of 71 patients were included in the study (mean age: 66 years), predominantly males (50/71, 70%), mean APACHE II score 26.04 ±10.56. Results showed an excellent inter-rater correlation (ICC) between raters (ICC scores > 0.97). Self-report NRS (numeric rating scale) scores were available from 58/71 patients (82%). Patients’ self-reported pain and CPOT showed a very strong correlation (Spearman’s R > 0.85, p < 0.0001). The CPOT has high diagnostic value for detection of presence of patients’ self-reported pain (ROC AUC = 0.938 for rater A and 0.951 for rater B, p < 0.0001). CPOT score ≥ 2 is an optimal cut-off to detect pain during a nociceptive procedure. A significantly higher mean CPOT score during a nociceptive procedure as compared to a non-nociceptive procedure or at rest was found (p < 0.0001).

Conclusions:
This study shows that the Polish version of the CPOT can be used to assess pain in critically ill patients with no hypnotic, opioid-based analgo-sedation. Polish CPOT scores correlated well with patients’ self-reported presence of pain and showed excellent inter-rater reliability. This makes the Polish version of the CPOT a reliable pain assessment tool.