Background: The assessment of prognosis in critically ill patients is crucial for the intensive care units (ICU) ability to provide high-quality care. Many patients in the ICU experience pain, leading to considerable suffering and potentially resulting in long-term consequences such as chronic pain and post-traumatic stress disorder. Instruments such as the Critical Care Pain Observation Tool and the Behavioral Pain Scale play a vital role in assessing pain in patients who are unable to express their discomfort verbally. The study’s objective was to compare the scales and find which scale helps to measure pain accurately.

Methods: This study was conducted using the comparative research design among 100 ICU patients, who were selected by consecutive sampling technique at intensive care unit of selected hospitals, Chennai. Pain assessment was done using critical care pain observation tool and behavioral pain scale simultaneously to identify the severity of pain from the patients on mechanical ventilation admitted in ICUs.

Results: Pain Assessment showed significant difference in perceived pain at rest based (2 ±3.34 & 4.3±0.7), during invasive procedure (5.01±2.34 & 6.4±2.1) using CPOT and BPS respectively. But there was no significant difference in perceived pain during non-invasive procedures based on CPOT (3.5±2.3) and BPS (5.28 ±2.05). There was a moderate to strong correlation between the CPOT and BPS pain assessment scale p<0.01 during rest, invasive procedure and non-invasive procedure. The ROC curve depicts that there is more area under the curve is observed in the CPOT (0.25) than in BPS (0.209).

Conclusion: The findings indicate that the CPOT scale demonstrates greater efficacy than the BPS in evaluating pain levels in critically ill patients who are receiving mechanical ventilation.