Background & aims: Nutritional status is a significant issue in an aging society; however, the impact of the nutritional status of older individuals using long-term care services on the caregiving burden remains unclear. This systematic review and meta-analysis aimed to investigate the impact of nutritional issues on adverse outcomes in older individuals using long-term care services.

Methods: We used data from the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Web of Science, CINAHL, and Ichu-shi Web databases. Original articles published in English or Japanese between January 2000 and July 2022 were included. The inclusion criteria were interventional and observational studies on individuals using long-term care services with aged ≥65 years and a focus on body weight or weight loss. Data on adverse outcomes related to caregiving burden, including the number of people requiring care, mortality, complications, activities of daily living (ADL), and quality of life, were collected.

Results: The literature search yielded 7873 studies, of which 35 were ultimately included. Seven observational studies investigated mortality outcomes, and seven examined ADL outcomes. The meta-analysis revealed significantly higher mortality rates in individuals classified as underweight (BMI <18.5 kg/m(2)) than in those with BMI ≥18.5 kg/m(2) (risk ratio [RR] 1.49; 95 % confidence interval [CI] 1.31 to 1.73, 0.22; I(2) 93 %). Further, on categorising the participants based on a BMI cutoff of 25 kg/m(2), those with a BMI of <25 kg/m(2) had a significantly increased mortality rate (RR 1.21; 95 % CI 1.04-1.40; I(2) = 98 %). BMI and weight loss did not affect ADL.

Conclusions: Our findings indicate that underweight and weight loss are significantly associated with increased mortality in older individuals using long-term care services. Therefore, appropriate weight management is recommended for this population. However, further research is necessary owing to the high heterogeneity observed in this study.