Abstract
BACKGROUND: The number of frail older people is increasing worldwide, and all countries will be confronted with their growing needs for healthcare and social support. The aim of this umbrella review was to summarize the evidence on the factors associated with frailty in older people, using a socioecological approach. METHODS: PubMed (MEDLINE), Scopus, Web of Science, ScienceDirect, Hinari (research4life), and the Trip database were systematically searched up to April 2023. Systematic reviews of observational studies that explored factors associated with frailty in older adults aged 60 years and over were considered for inclusion. No language, geographical or setting restrictions were applied. However, we excluded systematic reviews that investigated frailty factors in the context of specific diseases. The Joanna Briggs Institute Critical Appraisal Checklist for Systematic Reviews and Research Syntheses and the ROBIS tool were used to assess the quality and risk of bias in the included studies. RESULTS: Forty-four systematic reviews were included, covering 1,150 primary studies with approximately 2,687,911 participants overall. Several risk factors, protective factors and biomarkers were found to be associated with frailty, especially in community-dwelling older people, including 67 significant associations from meta-analyses. The certainty of the evidence was rated as moderate or reached moderate levels for seven factors relevant to older people. These factors include depression (OR 4.66, 95% CI 4.07 to 5.34), loneliness (OR 3.51, 95% CI 2.70 to 4.56), limitations in activities of daily living (OR 2.59, 95% CI 1.71 to 3.48), risk of malnutrition (OR 3.52, 95% CI 2.96 to 4.17), Dietary Inflammatory Index score (OR 1.24, 95% CI 1.16 to 1.33), maximal walking speed (Standardized Mean Difference (SMD) -0.97, 95% CI -1.25 to -0.68), and self-reported masticatory dysfunction (OR 1.83, 95% CI 1.55 to 2.18). Additionally, only greater adherence to a Mediterranean diet showed a high level of evidence (OR 0.44, 95% CI 0.31 to 0.64). CONCLUSIONS: This umbrella review will provide guidance for prevention strategies and clinical practice by promoting healthy lifestyles and addressing all modifiable risk factors associated with frailty. Future systematic reviews should consider heterogeneity and publication bias, as these were the main reasons for downgrading the level of evidence in our review. REGISTRATION: PROSPERO 2022, CRD42022328902.