Background: This study evaluated the reliability and validity of the Cardiac Analgesic Assessment Scale (CAAS) as a postoperative pain instrument for children after cardiac surgery.
Methods: Two prospective studies included 69 children (aged 0-16 years) admitted to the intensive care following cardiac surgery with a sternotomy incision. Four concurrent observers performed paired observations with the CAAS or a visual analogue scale (VAS) for 32 patients. After a stimulus to the patient, two nursing observers independently scored the patient with the CAAS, and another two independent nursing observers simultaneously scored the patient using a VAS. In the second part of this study the CAAS was evaluated with respect to its ability to detect changes in pain status and responses to analgesia over time in 37 patients.
Results: Interrater reliability, represented by Lin's concordance correlation coefficient proved to be almost perfect for the CAAS score 0.97 (95% CI: 0.95, 0.99). About 91% of patients received the same total CAAS score from the two raters. The dichotomized CAAS scores of the two nurses indicated that in 97% of cases the nurses agreed upon whether there was an indication for treatment of pain. The CAAS was shown to significantly reflect changes in pain status over time. The average Spearman's rank correlation between VAS and CAAS was low (0.27), indicating that CAAS did not correlate well with VAS.
Conclusion: This study provides evidence that postoperative pain in sedated and intubated children after cardiac surgery can be assessed reliably using a formal pain tool.