Factors associated with the progression of deficit accumulation frailty among adults with an intellectual disability: a systematic review revealing research gaps

Background: People with an intellectual disability are more likely to experience frailty earlier in life and with greater severity compared to the general population. There is growing consideration of determinants of frailty and identifying factors which may influence the change in frailty status over time. The objective of this review was to investigate factors associated with the progression of frailty over time among adults with an intellectual disability. Methods: A systematic review of literature was conducted using PRISMA guidelines to identify studies reporting factors associated with transitions and trajectories in deficit accumulation frailty among adults with an intellectual disability. The following eligibility criteria was used: defined frailty as deficit accumulation; longitudinal design; reported at least one individual characteristic associated with change in frailty status; sample was people with an intellectual disability aged ≥18 years; English language. No limitation on publication date was applied. Studies which did not measure frailty according to deficit accumulation, did not report the frailty measure used, or had a cross-sectional design were excluded. Selected studies were assessed for quality using the Critical Appraisal Skills Programme (CASP) framework. Results: In total, two studies qualified for inclusion in this review. Findings revealed that frailty defined as deficit accumulation is a dynamic process and improvements are possible. Changes in the direction of frailty states over time among adults with an intellectual disability may be influenced by several factors including baseline frailty status, age, the presence of Down syndrome, functional ability, cognitive ability, living in a group home, and the use of nursing services and therapies. Conclusions: There is a relative paucity of research on frailty among adults with an intellectual disability and the evidence base must be grown. Exploration of the social domain of frailty in this group should be a priority of future research. PROSPERO registration: 179803 (05/07/2020)