Incidence and associated factors of malnutrition among older people in nursing homes: a systematic review and meta-analysis

BACKGROUND: Malnutrition is prevalent among older people in nursing homes, and assessing associated factors of malnutrition is critical for successful malnutrition prevention interventions. This study aimed to systematically evaluate the incidence and associated factors of malnutrition in older people living in nursing homes. METHODS: PubMed, Embase, Web of Science, CINAHL, China Biological Medicine (CBM), Wan Fang, and China National Knowledge Infrastructure (CNKI) were comprehensively searched for observational studies investigating the incidence and associated factors of malnutrition among older people in nursing homes from inception to September 20, 2024. Two investigators independently selected the literature, evaluated their quality, and extracted relevant data. RESULTS: A total of 25 studies comprising 51,915 cases were included. The prevalence of malnutrition in nursing homes was 22% (95% CI: 0.19-0.25). Sociodemographic-associated factors of malnutrition among older people in nursing homes included age (OR = 2.39, 95%CI: 1.87-3.07), female (OR = 1.63, 95%CI: 1.34-1.99), marital status (OR = 1.37, 95%CI: 1.11-1.69), high cultural literacy (OR = 0.1, 95%CI: 0.02-0.49), denture (OR = 2.3, 95%CI: 1.17-4.51), and lack of exercise (OR = 1.25, 95%CI: 1.09-1.43). Physical and physiological function factors included care dependence (OR = 2.44, 95%CI: 1.99-3.00), disability for activities of daily living (OR = 3.37, 95%CI: 1.90-5.96), health self-assessment (OR = 2.05, 95%CI: 1.51-2.77), chewing function (OR = 1.77, 95%CI: 1.05-2.99), swallowing function (OR = 3.12, 95%CI: 2.21-4.41), intake (OR = 3.68, 95%CI: 1.72-7.86), appetite (OR = 7.59, 95%CI: 4.19-13.76), high BMI (OR = 0.29, 95%CI: 0.11-0.77), and pressure ulcer (OR = 1.74, 95%CI: 1.52-2.00). Disease-related associated factors included dementia (OR = 1.63, 95%CI: 1.54-1.74), depression (OR = 2.31, 95%CI: 1.24-4.29), frailty (OR = 3.37, 95%CI: 1.22-9.29), 1 < illness < 3 (OR = 3.86, 95%CI: 2.14-6.97), illness ≥ 3 (OR = 5.76, 95%CI: 2.81-11.79), diseases of the digestive system (OR = 1.31, 95%CI: 1.20-1.44), and cancer (OR = 1.26, 95%CI: 1.11-1.41). However, it remained unknown whether the use of medication (OR = 3.14, 95%CI: 0.38-25.77), diabetes (OR = 0.67, 95%CI: 0.49-0.93), and diseases of the respiratory system (OR = 1.55, 95%CI: 0.77-3,15) were associated with malnutrition. CONCLUSIONS: Malnutrition is a widespread problem among older people residing in nursing homes due to various physiological, psychological, social, and lifestyle factors. Future research should focus on developing risk prediction models based on these influencing factors, creating intervention programs, and conducting large-scale randomized controlled trials across multiple centers. TRIAL REGISTRATION: The study was registered in the International Database of Prospectively Registered Systematic Reviews (PROSPERO): CRD42023477611.