Background Self report is considered to be the “gold standard” of pain assessment but is frequently unobtainable in the ICU. The psychometric properties of the COMFORT-Behaviour (COMFORT-B) scale have been evaluated in children under the age of 3 years.

Aim and objectives To establish the reliability and validity of the COMFORT-B scale in children > 3 years of age in a PICU setting.

Methods A prospective observational study was performed using a repeated measures design in children from 3–17 years in two intensive care and high-dependency units in Ireland. Interrater reliability was tested among nurses using linearly weighted kappa, Cronbach α was applied to test internal consistency of the COMFORT-B scale and concurrent validity involved comparing COMFORT-B with the FLACC and Numeric Rating Scale score of nurses.

69 paired nursing assessments to test the interrater-reliability of the COMFORT-B scale was performed. With a high interrater-reliability of Cronbach 0.87, Single nurse observations were commenced of the COMFORT-B, NRS and FLACC/Self-report scores at specific four-hourly intervals over the first 48 h of each admission.

Results Data in 19 patients (age 3 to 17 years) was collected for the pilot study. Initial compliance of 4% increased to over 80%. Interrater reliability between COMFORT, FLACC and NRS remained high throughout the study.

Conclusion The COMFORT-B is suitable for use in children and adolescents from 3–17years.