Defining and measuring preclinical mobility limitation: An expert consensus exercise informed by a scoping review.

Early change in function in older adults has been termed preclinical disability (PCD). PCD has been understudied compared to other stages of disability because it is unlikely to receive comparative priority in clinical settings. It has major implications for prevention and population health as it may be the optimal time to intervene to prevent further decline. A standardised approach to research in PCD, including a common definition and measurement approaches, is needed to advance this work. The process to establish how PCD should be defined and measured was undertaken in 2 stages: 1) a scoping review of the literature, which was used to inform 2) a web-enabled consensus meeting with content experts. The results of the scoping review and the consensus meeting support the use of the term preclinical mobility limitation (PCML) and that it should be measured using both patient-reported and performance-based measures. It was agreed that the definition of PCML should include modification of frequency and/or method of task completion, without overt disability, and that requisite mobility tasks include walking (distance and speed), stairs and transfers. Currently, there are few standardised assessments that can identify PCML. PCML is the term that most clearly describes the stage where people experience a change in routine mobility tasks, without a perception of disability. Further evaluation into the reliability, validity and responsiveness of outcome measures is needed to advance research on PCML.