Identifying longitudinal sustainable hierarchies in activities of daily living.

Activities of daily living serve as an indicator of progression in disability and rehabilitation. It is know that some of the measurement scales used show hierarchical properties indicating that activities of daily living are lost and gained in a consistent pattern. Few studies have investigated the extent to which these patterns are sustained across time and across a range of disability. The study aimed to investigate the hierarchical properties of the activity of daily living items in the ValGraf functional ability scale, to establish if there is a hierarchy of items in the scale and to study the sustainability of the hierarchy over time. Secondary analysis of a retrospective database from 13,113 people over 65 years in 105 nursing homes in northern Italy, between 2008 and 2013 was conducted. Data were gathered 6-monthly and analysed using Mokken scaling to identify a hierarchy of items in the scale and if this was sustainable over time. A sustainable hierarchy of items was observed running in difficulty from urinary incontinence to feeding. The hierarchical structure of the activities of daily living observed in the present study is stable over time meaning that changes in total score for these items can be compared meaningfully across time.