The study, led by Erika Renzi and colleagues including corresponding author Michele Innocenzio, is what methodologists call an overview of systematic reviews, a study of studies that sits at the very top of the evidence pyramid. Rather than examining individual trials, the team systematically gathered and analyzed reviews that had already synthesized primary research on multi-component healthcare interventions for adults aged sixty-five and older. To be included, a review had to evaluate interventions targeting older populations, which in the pooled evidence included people living with frailty, cognitive impairment, and dementia, and it had to report the use of at least one implementation theory, model, or framework, the conceptual scaffolding that researchers use to plan, execute, and evaluate the rollout of a health intervention. The search covered six major databases, including PubMed, CINAHL, Scopus, Web of Science, PsycINFO, and the Cochrane Library, from their inception through the end of December 2024, and the protocol was prospectively registered on PROSPERO under registration number CRD42023444113.

The methodological machinery behind the overview was deliberately rigorous. The authors followed the Cochrane Handbook for systematic reviews of health interventions and reported their work in line with the PRISMA 2020 statement, the international standard for transparent reporting of systematic reviews. After screening the literature, they included eight reviews in total: five systematic reviews, one systematic review with meta-analysis, and two scoping reviews. Together, these reviews covered a remarkable 16,727 older adults, giving the overview a substantial evidentiary footprint. Methodological quality of each included review was appraised with AMSTAR-2, a validated instrument for judging the reliability of systematic reviews, which allowed the team to weigh their conclusions with appropriate caution. The unit of analysis, however, was not the trials themselves but the implementation frameworks and outcome measures those reviews described.

Seven distinct implementation frameworks emerged from the analysis, and two names dominated the landscape. The first was RE-AIM, an acronym standing for Reach, Effectiveness, Adoption, Implementation, and Maintenance, which has become something of a lingua franca for researchers trying to think beyond average treatment effects and toward the practical realities of dissemination. The second was the framework developed by Proctor and colleagues, along with adaptations such as the version proposed by Peters and coworkers, which decomposes implementation into a set of discrete outcomes: acceptability, adoption, appropriateness, feasibility, fidelity, coverage, sustainability, penetration, and cost. Alongside these heavyweights, the reviews also employed process models such as Knowledge-to-Action and Knowledge Dissemination and Utilization, which describe stepwise pathways for moving research evidence into practice, as well as approaches like the Innovative Care for Chronic Conditions framework and the Continuity of Care model, which attend to the structural organization of health services around older patients.

The crucial analytical move in the overview was to map the outcomes reported across these reviews onto the implementation outcome domains defined by Proctor and colleagues and operationalized in the World Health Organization’s practical guide on implementation research. This mapping exposed a striking inconsistency. Implementation outcomes, the team found, were reported unevenly across the evidence base and were frequently inferred from proxy indicators, indirect measurements such as attendance rates or staff survey responses, rather than from instruments explicitly aligned with WHO definitions. In other words, even when researchers believed they were evaluating implementation, they were often measuring something adjacent to it, leaving readers to guess whether two studies reporting the same outcome label were actually capturing the same phenomenon.

Some outcomes fared better than others. Acceptability, the degree to which an intervention is judged agreeable and satisfactory by its recipients and providers, was the only implementation outcome consistently reported across all eight reviews, suggesting that the patient and caregiver experience is now firmly on the research agenda. Adoption, the willingness of organizations and practitioners to take up an intervention, along with coverage and sustainability, were assessed in some reviews but not others, producing a patchy picture of how often programs actually enter routine care and survive there. At the bottom of the hierarchy sat appropriateness and feasibility, each evaluated in only three of the eight reviews, and implementation costs received similarly sparse attention. These omissions matter enormously, because a program that older adults enjoy but that no clinic can afford, staff, or schedule is a program that will never reach scale.

The authors interpret this pattern as a gap between the nominal use of implementation frameworks and their consistent operationalization, a gap with two roots. The first is structural: not every framework covers the full set of implementation outcomes, so a team that adopts RE-AIM, for instance, may simply have no designated slot for measuring appropriateness or cost. The second is behavioral: primary studies apply outcome definitions inconsistently, so even when a framework does specify what should be measured, the underlying trials supply data in incompatible forms. The result is an evidence base in which the vocabulary of implementation science is widely spoken but its grammar is applied loosely, making it difficult to compare programs, aggregate findings, or draw confident conclusions about which strategies actually get multi-component interventions into the hands of older adults who need them.

Why should the general reader care about what looks like an arcane dispute over outcome definitions? Because the demographic stakes could hardly be higher. Societies across Europe, North America, and Asia are aging rapidly, and the dream of active ageing, preserving physical, cognitive, and social function deep into later life, depends on interventions that are inherently multi-component and therefore inherently complex to deliver. Frailty, cognitive impairment, and dementia are precisely the conditions where fragmented, single-domain care fails, and where coordinated programs combining exercise, nutrition, cognition, and social support show the greatest promise. Every implementation failure represents lost health for older people and wasted resources for health systems already strained by rising demand. Standardized, comparable implementation evidence is the infrastructure that would let policymakers know not just whether a program can work, but whether it will work in their hospitals, clinics, and communities.

The overview, which was supported by the Next Generation EU programme through the National Recovery and Resilience Plan as part of the AGE-IT project on ageing well in an ageing society, closes with a clear prescription rather than a shrug. The authors call for more standardized reporting of implementation outcomes, explicit alignment with the definitions set out by Proctor and colleagues and the WHO practical guide, and deliberate attention to the neglected domains of feasibility, appropriateness, and cost. They also note that reliance on proxy indicators should give way to measures that genuinely operationalize each outcome. None of this diminishes the value of the interventions themselves; instead, it reframes the challenge. The science of active ageing has largely solved the question of what to offer older adults. The next frontier, this overview makes plain, is proving, with the same rigor applied to clinical endpoints, that those offerings can actually be implemented, sustained, and scaled in the untidy reality of everyday care.

Subject of Research: Implementation science of multi-component interventions promoting active ageing in older adults

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

Article References: Renzi, E., Parrinello, E., Innocenzio, M., Covelli, A., Baccolini, V., De Vito, C., Marzuillo, C., Cincotti, F., Villari, P., & Massimi, A. (2026). How to ensure the implementability of multi-component interventions to improve active ageing in older people? An overview of the evidence of systematic reviews. BMC Geriatrics. https://doi.org/10.1186/s12877-026-08325-6

Image Credits: AI Generated

DOI: 10.1186/s12877-026-08325-6

Keywords: active ageing, older adults, implementation science, systematic reviews, RE-AIM, Proctor framework, multi-component interventions, frailty, dementia, WHO practical guide, geriatrics, implementation outcomes