Report of having slowed down: Evidence for the validity of a new way to inquire about mild disability in elders

Abstract

Background. Mild disability in elderly persons may be detected by eliciting reports of modified task performance, even in the absence of reported difficulty. This study provides evidence for the validity of one type of modification, namely, slowing, as a measure of mild walking disability. Methods. Community-dwelling elders (N = 287) were questioned about whether they were walking indoors as quickly as they had 1 year before and 10 years before. Construct validity was assessed by the degree to which responses to these two questions were logically consistent with a general decline in walking speed, and by determining whether reported slowing was associated with concurrent reports of difficulty walking and with measured gait speed. Predictive validity in subjects without reported difficulty walking was gauged by the association of reported slowing with adverse walking outcomes at 1-year follow-up. Results. Reports of slowing over 10- and 1-year periods were almost uniformly consistent with a general decline in speed. Reported slowing was significantly associated with reported difficulty walking and with slower gait speed. In the subgroup of elders initially reporting no difficulty walking, reported slowing significantly predicted incident difficulty walking at follow-up, as well as other adverse walking outcomes. For example, among elders who reported slowing, 7%, 10%, and 19% developed new difficulty walking indoors, new difficulty walking outdoors, or stopped walking for pleasure, compared with 0%, 0%, and 3% for those who had not reported slowing (p < .05). Conclusions. This study provides evidence for the construct and predictive validity of one type of task modification, namely, slowing in indoor walking. This work contributes to the development of new methods for measuring mild disability, which may in turn form the basis for clinical interventions based on the early identification of functional problems.