Psychometric properties of ability to contribute measurements as a domain of functional ability of older persons: a COSMIN systematic review

Background Older person's ability to contribute covers contributions divided into five subdomains: assisting friends and neighbours, mentoring peers and younger people, caring for family, engaging in the workforce and voluntary activity.Objective To evaluate the psychometric properties of ability to contribute measurements as a domain of functional ability of older persons using Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) methodology for systematic reviews.Methods A systematic search was performed in PubMed, Embase and PsycINFO databases, for observational studies published within the last 10 years. The measurement properties of these ability measures were evaluated against the COSMIN taxonomy. Risk-of-bias assessment was performed using the COSMIN Risk of Bias checklist.Results Of the 32,665 studies identified, we selected 19, of which the main purpose was to develop or validate an instrument or have related items that measure at least one of the subdomains. None of the instruments contained items that were fully related to the five subdomains, 60% (n = 12) were related to voluntary activities and 15% (n = 3) to mentoring peers and younger people. As for psychometric properties, two studies assessed content validity. Factor analysis was used to evaluate structural validity in 10 studies. Internal consistency was evaluated in 63% of the instruments and Cronbach's alpha ranges from 0.63 to 0.92. No study reported predictive validity. A very limited overview of their scope and limitations for their application was observed.Conclusions We found no single instrument measuring all subdomains of ability to contribute. We found several instruments containing items that could indirectly measure some of the subdomains of the ability to contribute.