Psychometric evaluation of the Pain Assessment in Advanced Dementia scale in an acute general hospital setting

Background: People with dementia are at risk of unplanned hospital admissions and commonly have painful conditions. Identifying pain is challenging and may lead to undertreatment. The psychometric properties of the Pain Assessment in Advanced Dementia (PAINAD) scale, in medical inpatients with dementia have not been evaluated. Methods: A secondary data analysis from a longitudinal study of 230 people with dementia admitted to two acute general hospitals in London, UK. Internal consistency, inter-rater reliability, test-retest reliability, concurrent validity, construct validity and discriminant validity of PAINAD were tested at rest and in movement. Results: This predominantly female (65.7%) sample had a mean age of 87.2 (Standard Deviation; SD = 5.92) years. Inter-rater reliability showed an intra-class correlation (ICC) of 0.92 at rest and 0.98 in movement, test-retest reliability ICC was 0.54 at rest and 0.66 in movement. Internal consistency was 0.76 at rest and 0.80 in movement (Cronbach's alpha). Concurrent validity was weak between PAINAD and a self-rating level of pain (Kendall's Tau; tau = 0.29; p > 0.001). There was no correlation between PAINAD and a measure of behavioural and psychological symptoms of dementia, suggesting no evidence of convergent validity. PAINAD scores were higher during movement than rest, providing evidence of discriminant validity (z = -8.01, p < 0.001). Conclusions: We found good inter-rater reliability and internal consistency. The test-retest reliability was modest. This study raises concerns about the validity of the PAINAD in general acute hospitals. This provides an insight into pain assessment in general acute hospitals which may inform further refinements of the PAINAD.