Mega-Map of Systematic Reviews and Evidence and Gap Maps on Interventions and Programs for Age-Friendly Environments

Background: Population aging is a global reality. As we achieve longer life expectancy, a longer healthy life is not yet a reality for everyone. Age-friendly environments (such as in the home, community, cities) foster healthy aging by building and maintaining intrinsic capacity across the life course and enabling greater functional ability in someone with a given level of capacity. Developing age-friendly cities and communities (AFCC) has become a widely adopted strategy for promoting age-friendly environments, focusing on AFCC interventions across eight domains: Transportation, Housing, Outdoor spaces and buildings, Social participation, Respect and social inclusion, Civic participation and employment, Communication and information, and Community support and health services, as outlined in the WHO AFCC framework. Stakeholders face challenges in identifying and using relevant evidence in AFCC in part due to the lack of a comprehensive evidence map and a systematic assessment of research gaps. Objectives: The aims of this mega-map were to identify, map, and describe existing evidence from systematic reviews and evidence and gap maps (EGMs) on interventions and programs to create and sustain age-friendly environments; to identify existing gaps in methods, interventions, outcomes, and geographies to assist researchers and policymakers in making evidence-informed research and funding decisions. Search methods: As this is a mega-map, only systematic reviews and EGMs were eligible for inclusion. A search strategy was iteratively developed using terms from key systematic reviews on age-friendly environments and refined through trial searches and expert input. Comprehensive searches were conducted across more than 40 sources—including 18 major academic databases and 23 organizational websites for grey literature—covering evidence up to August 2024, with an additional search of the AgeInfo database completed in October 2025. Searches were performed without language restrictions and supplemented by targeted Chinese searches conducted by native-language experts. Selection criteria: The population of interest comprised adults aged 50 years and older living in cities and communities of any size, across urban, peri-urban, and rural areas worldwide. Any intervention falling within the eight age-friendly domains or AFCC programs was eligible for inclusion. No restrictions were applied regarding intervention comparators. Data collection and analysis: Records were managed in EPPI-Reviewer, with deduplication, quality-assured screening, citation chasing, and expert consultation to capture all relevant evidence. Data extraction followed a piloted, standardized coding tool, and domain and outcome mapping were validated through independent re-mapping to ensure consistency and reliability. Quality appraisal of included systematic reviews was conducted using the Rapid Appraisal Fast-and-Frugal Decision Tree approach. The results were presented in an online interactive mega - map that includes filters for type of study, population, intervention characteristics (age-friendly domains, implementation level, and implementation instruments), and equity focus (based on PROGRESS-Plus). Outcomes were categorized into intermediate outcomes, intrinsic capacity, functional ability, late health outcomes, and economic impact. Main results: In total, 1,545 studies were included in the mega-map (1,542 systematic reviews and three EGMs) published between 2002–2025. Most included evidence was published in English (n = 1,397), with an additional 145 systematic reviews identified in Chinese. Overall, most reviews and all EGMs included both male and female participants, with the ≥60 - year age group most frequently represented. Evidence coded as having an equity focus was limited. The evidence was concentrated within a narrow range of intervention–outcome combinations and was predominantly drawn from urban settings in high-income countries. Evidence from systematic reviews was identified across all eight age-friendly domains and AFCC programs. Overall, 1,468 reviews were rated as lower quality and 74 as higher quality. Evidence was concentrated in the domains of Community Support and Health Services (n = 1,410 lower-quality; n = 65 higher-quality), followed by Communication and Information (n = 213 lower-quality; n = 13 higher-quality) and Social Participation (n = 207 lower-quality; n = 9 higher-quality). The domains of Housing (n = 49 lower-quality; n = 5 higher-quality) and Outdoor Spaces and Buildings (n = 36 lower-quality; n = 3 higher-quality) accounted for a smaller share of the evidence base. In contrast, Transportation (n = 8 lower-quality), Civic Participation and Employment (n = 7 lower-quality), and Respect and Social Inclusion (n = 21 lower-quality; n = 4 higher-quality) were sparsely represented. Evidence on AFCC programs was particularly limited, with only two lower-quality systematic reviews identified. Most interventions were implemented at the individual level (n = 1317 lower - quality; n = 65 higher - quality) and delivered through information, education and communication (n = 887 lower-quality; n = 55 higher-quality), followed by infrastructure, technology, and built environment (n = 792 lower-quality; n = 41 higher-quality) instruments. Across outcomes, the evidence was concentrated in intrinsic capacity (n = 1,343 lower-quality; n = 65 higher-quality), intermediate outcomes (n = 1,054 lower-quality; n = 54 higher-quality), late health outcomes (n = 792 lower-quality; n = 42 higher-quality), and functional ability (n = 778 lower-quality; n = 43 higher-quality), while economic impact outcomes were the least represented (n = 240 lower-quality; n = 18 higher-quality). Evidence from EGMs was limited to three maps covering four of the eight age-friendly domains: Community Support and Health Services (n = 3), Social Participation (n = 2), Communication and Information (n = 2), and Respect and Social Inclusion (n = 1). No EGM was identified for AFCC programs. Similar to the systematic reviews, interventions were primarily implemented at the individual level (n = 3) and delivered through information, education, and communication (n = 2) and infrastructure, technology, and built environment instruments (n = 2). Outcomes were concentrated in intrinsic capacity (n = 3), intermediate outcomes (n = 3), and late health outcomes (n = 3), with less evidence on functional ability (n = 2) and economic impact outcomes (n = 1). Authors’ conclusions: This mega-map provides a comprehensive synthesis of evidence on interventions across the eight age-friendly domains and AFCC programs. Although the evidence is large, it is unevenly distributed across intervention domains, outcomes, populations and geographies. Important gaps were identified in the evidence on AFCC programs, national and subnational level interventions, economic outcomes, and equity, as well as the limited representation of low-and middle-income countries and rural areas. These findings can inform priorities for future research and funding decisions for age-friendly environments. Addressing these gaps will require coordinated global efforts to improve the scope, geographic distribution, quality, and policy relevance of the evidence base, including the development of a standardized intervention taxonomy and targeted evidence syntheses in underrepresented areas of the WHO AFCC framework, particularly AFCC programs. Including evidence published in a wider range of languages could strengthen the evidence base used to inform age-friendly policy and practice across diverse contexts.