Objective: To translate critical care pain observation tool (CPOT) and behavioral pain scale (BPS) into Thai language, and to validate the Thai version of these pain assessment tools in postoperative mechanically ventilated adult intensive care unit (ICU) patients.
Material and Method: This is a prospective study. After translation, both pain scales were tested for concurrent validity, discriminant validity, criterion validity, and inter-rater reliability in patients who were intubated during the postoperative period. Opinions regarding practicality were elicited via questionnaires from nurses who had been using and were familiar with these two pain scales.
Results: Four hundred and eighty-four observations from 27 included patients were analyzed. Concurrent validity was supported by positive correlations between scales, which ranged from r = 0.74 to r = 0.78 (p<0.01). Both scales showed a trend toward agreement with routine clinical decisions to treat postoperative pain. Discriminant validity was demonstrated by high scores (BPS 5, CPOT 3) in higher pain situations before giving analgesics, and by lower pain scores (BPS 4, CPOT 2) in less painful situations after pain medication had been given. Both scales showed good inter-rater reliability (intraclass correlation coefficient = 0.72 to 0.90).
Conclusion: The Thai version BPS and CPOT are valid and reliable tools for assessment of pain in postoperative mechanically ventilated adult ICU patients. Further studies are needed to evaluate the value and utility of these scales for improving pain management in a critical care setting in Thailand.

Keywords: Thai version, Validated, Critical care pain observation tool, CPOT, Behavioral pain scale, BPS, Adult ICU patients