Assessing pain in patients with severe cerebral palsy: Development, reliability, and validity of a pain assessment instrument for cerebral palsy

Objectives: To develop the Pain Assessment Instrument for Cerebral Palsy (PAICP) and to study its test-retest reproducibility and construct validity. Design: Cross-sectional validation study. Setting: Homes for severely handicapped. Participants: A total of 164 adults with severe cerebral palsy (CP), caregivers, and physiotherapists, and 9 healthy children. Interventions: The PAICP contains drawings of situations, some situations of which usually produce pain. Patients rate the pain associated with each activity using a Faces Pain Scale. Reproducibility and construct validity was assessed in a pilot study with CP patients and healthy children. Construct validity and agreement between the pain scores of the patients and proxies was assessed in 160 patients with severe CP. Main Outcome Measure: Pain score on the PAICP. Results: The measure showed adequate test-retest reproducibility. A significant difference was found between the mean scores for "painful" and "not painful" situations. We also found moderate agreement between the scores of the patients and proxies for daily activities but only for those activities in which the proxies were personally involved. Conclusions: The PAICP has adequate test-retest reproducibility and construct validity. It provides an indication of the pain experienced by patients in situations in which proxies are not personally involved and may also be more valid than proxy measures for other situations.