A hierarchical categorisation of tasks in mobility disability

Purpose.In the field of long-term care, disability usually refers to difficulties in instrumental activities of daily living (IADL) or basic activities of daily living (BADL); this term may also refer to difficulties in mobility for those more interested in preventive intervention or general health promotion. The aims of this study were to (1) categorise a complete set of mobility tasks according to a revealed hierarchy, and (2) examine the relationship between this mobility hierarchy and IADL/BADL disabilities. Methods.We categorised nine mobility tasks according to appearance order in self-reported difficulties data obtained from a Taiwanese national database of community-dwelling elders aged over 65. We also performed correlation tests to explore the relationships of these mobility tasks with six tasks each of IADL and BADL. Results.The results revealed a three-level hierarchy of mobility disability: (1) mild disability indicated by difficulties in four mobility tasks, which correlated with difficulty in one IADL task; (2) moderate disability indicated by difficulties in three mobility tasks, which correlated with difficulties in most IADL tasks; and (3) severe disability indicated by difficulties in two mobility tasks, which correlated with difficulties in all BADL tasks. The same hierarchy was observed for males and females. Conclusions.There is a clear hierarchical structure of mobility disability that correlates differently with IADL and BADL disabilities. These results suggest that different mobility tasks should be included in disability assessments to suit specific purposes.