How to ensure the implementability of multi-component interventions to improve active ageing in older people? An overview of the evidence of systematic reviews

Implementation research supports the translation of evidence-based interventions into routine care by identifying effective implementation strategies, measuring implementation outcomes, and planning for sustainability across diverse settings. This is particularly relevant for multi-component healthcare interventions aimed at promoting active ageing in older populations, where implementation is often complex and context dependent. This overview aimed to: (1) identify and characterize the implementation theories, models, and frameworks (TMFs) used in systematic and scoping reviews of multi-component healthcare interventions promoting active ageing in older adults; and (2) examine how implementation outcomes, as defined by Proctor et al. [1] and operationalized in the WHO practical guide, were assessed and reported across the evidence synthesized in these reviews. We conducted an overview of systematic reviews guided by the Cochrane Handbook and reported in accordance with PRISMA 2020. We searched PubMed, CINAHL, Scopus, Web of Science, PsycINFO, and the Cochrane Library from inception to 31 December 2024. We included systematic reviews (with or without meta-analysis) and scoping reviews published in English or Italian that evaluated multi-component healthcare interventions targeting adults aged ≥ 65 years and reported the use of at least one implementation theory, model, or framework. We extracted the implementation framework(s) applied and mapped reported outcomes to the implementation outcome domains as defined by Proctor et al. [1] and operationalised in the WHO practical guide. Methodological quality was assessed using AMSTAR-2. Eight reviews (five systematic reviews, one systematic review with meta-analysis, and two scoping reviews) were included, covering 16,727 adults aged ≥ 65 years and targeting populations with conditions such as frailty, cognitive impairment, and dementia. Seven implementation frameworks were identified, with RE-AIM and Proctor’s framework (including adaptations such as Peters’) most frequently used, alongside process models (Knowledge-to-Action; Knowledge Dissemination and Utilization) and other approaches (e.g., ICCC and CICI). Across reviews, implementation outcomes were reported inconsistently and were often inferred from proxy indicators rather than measures explicitly aligned with WHO definitions. Acceptability was consistently reported in all reviews, whereas adoption, coverage, and sustainability were variably assessed. Appropriateness and feasibility were least frequently evaluated, each reported in only 3/8 reviews. This overview identifies a gap between the use of implementation frameworks and the consistent operationalization and reporting of implementation outcomes as defined by Proctor et al. [1] and the WHO practical guide, reflecting both structural limitations in framework coverage and inconsistent application of outcome definitions in primary studies in multicomponent interventions for older adults. Reliance on proxy indicators and limited assessment of feasibility, appropriateness, and implementation costs highlight priorities for more standardized reporting to support real-world implementation and scale-up. PROSPERO CRD42023444113.